EXHIBIT 99

15985 East High Street

P. O. Box 35

Middlefield, Ohio 44062

Phone: 440/632-1666     FAX: 440/632-1700

www.middlefieldbank.com

PRESS RELEASE

Middlefield Banc Corp. Reports Financial Results for the 2015 Third Quarter

MIDDLEFIELD, OHIO, October 22, 2015 ¿  ¿  ¿  ¿ Middlefield Banc Corp. (NASDAQ: MBCN) today reported financial results for the three and nine months ended September 30, 2015.

2015 Third Quarter Financial Highlights Include (on a year-over-year basis unless noted):

“We are proud of the strong profitability we were able to achieve in the 2015 third quarter, driven by increases in both interest and noninterest income, and controlled expenses,” stated Thomas G. Caldwell, President and Chief Executive Officer. “Since the start of the year our loan portfolio has increased 8.4% primarily due to higher real estate loans reflecting the investments we have made in our advertising strategy, product lines, and associates. This growth helped drive a 5.8% year-over-year increase in interest and fees generated on loans in the 2015 third quarter, despite a lower yield on earnings assets. We did a good job managing expenses during the quarter, as our funding costs declined 4.0% year-over-year, while noninterest expenses declined 10.5% sequentially. We remain committed to our growth oriented business plan, while proactively managing expenses. We have strengthened our team of seasoned lenders and look forward to their growing contributions in the coming quarters.”

Net income for the 2015 third quarter was $2.0 million, or $0.96 per diluted share, compared to net income for the 2014 third quarter of $1.9 million, or $0.93 per diluted share. Net income for the nine months ended September 30, 2015 was $5.1 million, or $2.47 per diluted share, compared to net income for the nine months ended September 30, 2014 of $5.3 million, or $2.59 per diluted share.

Annualized returns on average equity (“ROE”) and average assets (“ROA”) for the 2015 third quarter were 12.67% and 1.10%, respectively, compared with 13.55% and 1.13% for the 2014 third quarter. ROE and ROA were 10.83% and 0.97%, respectively, for the 2015 nine month period, compared with 12.74% and 1.06% for the same period last year.

Mr. Caldwell continued: “Over the past two years we have been communicating an investment strategy focused on building Middlefield’s brand within and around our communities. Highlights of this plan include enhancements made in the way customers interact with the bank and an expansion into secondary mortgage products, which has improved noninterest income by 10.2% through the first nine-months of 2015. The new loan production office in Mentor, Ohio increased our geographic footprint to Lake County and we expect this office to quickly contribute to higher loan growth, especially to commercial customers. Finally, we have also made investments throughout the year to create value for our shareholders, which includes increasing our quarterly dividend payment and the recent repurchase of nearly 10% of Middlefield’s common stock outstanding. As we enter the fourth quarter, our outlook is encouraging and is resulting from the strength in our core geographic markets, enhancements we have made to our product and service offerings, and growth in our financial results.”

Income Statement

Net interest income for the 2015 third quarter increased 4.7% to $6.2 million, compared to $5.9 million for the 2014 third quarter. For the 2015 nine month period, net interest income increased 3.8% to $18.4 million, compared to nearly $17.8 million for the same period last year. The net interest margin for the 2015 third quarter was 3.80%, compared to 3.99% for the same period of 2014. Year-to-date, the net interest margin was 3.88%, compared to 4.08% for the same period last year.

Noninterest income, compared to the same period last year, was up 11.9% for both the 2015 third quarter and year-to-date. The improvement to noninterest income in the 2015 third quarter, as well as the nine month period was primarily a result of higher investment gains, earnings on bank-owned life insurance, and gains on sale of loans.

Noninterest expense for the 2015 third quarter was $4.7 million, an increase of 6.5% from $4.4 million for the 2014 third quarter. Year-to-date, noninterest expense increased 11.2% to $14.7 million, compared to $13.2 million for the same period last year.

“Our asset quality remains strong, as we have grown assets and increased our loan portfolio,” said Donald L. Stacy, Chief Financial Officer. “Nonperforming assets for the 2015 third quarter declined 17.0% to $10.9 million, from $13.2 million in the prior year period. We are balancing loan growth with strict underwriting standards to manage risk. As a result, our allowance for loan and lease losses continues to decline, and represented 1.24% of total loans as September 30, 2015. From a capital perspective, Middlefield remains well capitalized as our Tier 1 capital to average asset ratio improved 16 basis points to 9.66% at the end of the 2015 third quarter. At September 30, 2015, the bank had $23.3 million in cash and cash equivalents on our balance sheet, and our net loans to total deposits were 80.4%. As a result of our excellent liquidity, capital position, and belief that our stock represents a compelling value, on October 5, 2015, we repurchased 196,635 shares, or 9.5% of Middlefield Banc Corp. common stock outstanding at $34.50 per share for a total cost of $6.8 million.”

Balance Sheet

Total assets at September 30, 2015 increased 4.9% to a record $710.6 million, from $677.5 million at December 31, 2014. Net loans at September 30, 2015 were $503.9 million, compared to $463.7 million at December 31, 2014. The 8.7% year-to-date improvement in net loans was a result of loan growth in both residential and commercial mortgages, which have increased 14.4% and 18.3%, respectively year-to-date. This was offset by a 12.5% reduction in commercial and industrial loans, and a 42.0% decline in construction loans.

Total deposits at September 30, 2015 increased 6.9% to $626.5 million from $586.1 million at December 31, 2014. The investment portfolio, which is entirely classified as available for sale, stood at $145.1 million at September 30, 2015, compared to $154.3 million at December 31, 2014.

Stockholders’ Equity and Dividends

Tangible stockholders’ equity increased 10.1% to $62.6 million for the 2015 third quarter, compared to $56.8 million at September 30, 2014. On a per share basis, tangible stockholders’ equity increased 9.0% to $30.23 at September 30, 2015 from $27.74 at September 30, 2014. The increase is the result of a higher level of retained earnings and accumulated other comprehensive income, which was offset by cash dividends paid to shareholders.

At September 30, 2015, the company had a Tier 1 leverage ratio of 9.66% up from 9.50%, at September 30, 2014, and 9.56% at June 30, 2015.

During the 2015 third quarter, the company paid a cash dividend of $0.27 per share, which is 3.8% higher than the amount paid in the 2014 third quarter. Year-to-date, the company has paid cash dividends of $0.80 per share, which is a 2.6% increase over the same period last year.

Asset Quality

The provision for loan losses for the 2015 third quarter was $105,000 compared to $70,000 for the 2014 third quarter. Year-to-date, the provision for loan losses was $210,000, compared to $370,000 for the same period last year. Nonperforming assets at September 30, 2015 were $10.9 million, compared with $13.2 million for the same period last year. Net charge-offs for the 2015 third quarter was $131,000, or 0.10% of average loans, annualized, compared to a reversal of $89,000 for the same period last year. Year-to-date net charge-offs were $736,000, or 0.20% of average loans, annualized, compared to $128,000, or 0.04% of average loans, annualized for the same period last year. The allowance for loan losses at September 30, 2015 was $6.3 million, or 1.24% of total loans, compared with $7.3 million, or 1.56% of total loans at September 30, 2014.

The following table provides a summary of asset quality and reserve coverage ratios.

Asset Quality History

(dollars in thousands)

Middlefield Banc Corp., headquartered in Middlefield, Ohio, is a bank holding company with total assets of $710.6 million at September 30, 2015. The bank operates 10 full service banking centers and an LPL Financial^® brokerage office serving Chardon, Cortland, Dublin, Garrettsville, Mantua, Middlefield, Newbury, Orwell, and Westerville. The Bank also operates a Loan Production Office in Mentor, Ohio. Additional information is available at www.middlefieldbank.com.

This press release of Middlefield Banc Corp. and the reports Middlefield Banc Corp. files with the Securities and Exchange Commission often contain “forward-looking statements” relating to present or future trends or factors affecting the banking industry and, specifically, the financial operations, markets and products of Middlefield Banc Corp. These forward-looking statements involve certain risks and uncertainties. There are a number of important factors that could cause Middlefield Banc Corp.’s future results to differ

materially from historical performance or projected performance. These factors include, but are not limited to: (1) a significant increase in competitive pressures among financial institutions; (2) changes in the interest rate environment that may reduce interest margins; (3) changes in prepayment speeds, charge-offs and loan loss provisions; (4) less favorable than expected general economic conditions; (5) legislative or regulatory changes that may adversely affect businesses in which Middlefield Banc Corp. is engaged; (6) technological issues which may adversely affect Middlefield Banc Corp.’s financial operations or customers; (7) changes in the securities markets; or (8) risk factors mentioned in the reports and registration statements Middlefield Banc Corp. files with the Securities and Exchange Commission. Middlefield Banc Corp. undertakes no obligation to release revisions to these forward-looking statements or to reflect events or circumstances after the date of this press release.

MIDDLEFIELD BANC CORP.

Consolidated Selected Financial Highlights

September 30, 2015 and 2014 and December 31, 2014

MIDDLEFIELD BANC CORP.

Consolidated Selected Financial Highlights

September 30, 2015 and 2014

(Dollar amounts in thousands)

(unaudited)