Exhibit 99.1

BUSINESS FIRST BANCSHARES, INC. ANNOUNCES FINANCIAL RESULTS FOR Q1 2018

Baton Rouge, LA – Business First Bancshares, Inc. (NASDAQ:BFST), parent company of Business First Bank, Baton Rouge, Louisiana, today announced its unaudited results for the quarter ended March 31, 2018, including record quarterly net income of $3.1 million, or $0.29 per diluted share, which reflected increases of $1.1 million and $0.02, respectively, from the quarter ended March 31, 2017. Core net income, which excludes nonrecurring income and expenses, was $3.6 million, or $0.34 per diluted share, which reflected increases of $2.3 million and $0.17, respectively, from the quarter ended March 31, 2017.

“Our company’s first quarter was the most meaningful quarter in our history,” said Jude Melville, President and CEO. “Our team consummated the merger of MBL Bank in under three months from the date of announcement, deepening our presence along the I-20 corridor in Northern Louisiana; we continued to achieve organic growth across our footprint in both our loan and deposit portfolios; and we prepared to list our stock on the NASDAQ Global Select stock exchange, a step we were able to accomplish early in the second quarter. Our franchise is building significant momentum and we look forward to performing for our clients and our shareholders over the course of 2018 as we continue working to be our region’s most impactful business-focused community banking institution.”

On April 19, 2018, Business First’s Board of Directors declared a quarterly dividend based upon financial performance for the quarter in the amount of $0.08 per share to the common shareholders of record as of May 15, 2018. The dividend will be paid on May 31, 2018, or as soon thereafter as practicable. The dividend reflects a $0.02 increase over the dividend paid for the prior quarter.

Quarterly Highlights

Financial Condition

As of March 31, 2018, Business First had total assets of $1.6 billion, total loans of $1.2 billion, total deposits of $1.3 billion, and total shareholders’ equity of $180.0 million, compared to $1.3 billion, $975.5 million, $1.1 billion, and $180.0 million, respectively, as of December 31, 2017.

Nonperforming loans as a percent of total loans held for investment decreased from 1.30% as of December 31, 2017 to 1.27% as of March 31, 2018. Nonperforming assets as a percent of total assets increased from 0.98% as of December 31, 2017 to 1.04% as of March 31, 2018, primarily due a $1.0 million increase in nonperforming assets related to the closure of two branch locations in the Greater Baton Rouge area, which were recorded as other repossessed assets.

Book value per common share was $17.52 at March 31, 2018, compared to $17.58 at December 31, 2017. Tangible book value per common share was $13.90 at March 31, 2018, compared to $16.72 at December 31, 2017. The decrease in book value and tangible book value per common share during the quarter is primarily attributable to (i) a $2.7 million increase in net unrealized losses in the securities portfolio, or $0.27 per common share, during the quarter primarily due to rising interest rates, and (ii) with respect to tangible book value, the completion of the acquisition of MBI on January 1, 2018, which added $28.5 million in intangible assets, or $2.77 per common share.

Operating Highlights

For the quarter ended March 31, 2018, net income was $3.1 million, or $0.30 per basic share and $0.29 per diluted share, compared to net income of $2.0 million, or $0.29 per basic share and $0.27 per diluted share, for the quarter ended March 31, 2017. Return on average assets, on an annualized basis, increased to 0.77% for the quarter ended March 31, 2018, from 0.70% for the quarter ended March 31, 2017. Return on average equity, on an annualized basis, increased to 6.94% for the quarter ended March 31, 2018, as compared to 6.91% for the quarter ended March 31, 2017. The increase in net income for the quarter ended March 31, 2018, compared to the same time period in 2017, can primarily be attributed to the acquisition of MBI, growth of the loan portfolio, and the enactment of the Tax Cuts and Jobs Act which lowered the effective corporate tax rate.

Notable nonrecurring events impacting earnings include the sale of a participation interest in an impaired credit acquired from American Gateway in 2015, which resulted in a $1.1 million increase in interest income for the quarter ended March 31, 2017, and the incurrence of $512,000 in noninterest expenses related to the acquisition of MBI in the quarter ended March 31, 2018. Core net income, which excludes nonrecurring income and expenses, for the quarter ended March 31, 2018 was $3.6 million, or $0.34 per diluted share, compared to core net income of $1.2 million, or $0.17 per diluted share, in the quarter ended March 31, 2017. As adjusted, core return on average assets and core return on average equity, in each case on an annualized basis, were 0.88% and 7.96% for the quarter ended March 31, 2018, compared to 0.43% and 4.27% for the quarter ended March 31, 2017.

For the quarter ended March 31, 2018, net interest income totaled $14.5 million, and net interest margin and net interest spread were 3.97% and 3.75%, respectively, compared to $11.6 million, 3.87%, and 3.57% for the quarter ended December 31, 2017 and $10.6 million, 4.04%, and 3.84%, respectively, for the quarter ended March 31, 2017. The average yield on the loan portfolio was 5.32%, compared to 5.22% for the quarter ended December 31, 2017 and 5.34% for the quarter ended March 31, 2017, and the average yield on total interest-earning assets was 4.72%, compared to 4.57% for the quarter ended December 31, 2017 and 4.63% for the quarter ended March 31, 2017. These metrics were impacted during the quarter ended March 31, 2017 by the sale of a participation interest in an impaired credit acquired from American Gateway in 2015. Excluding the effect of this transaction, for the quarter ended March 31, 2017, net interest income was $9.4 million, net interest margin and net interest spread were 3.60% and 3.40%, respectively, and average yield on the loan portfolio and on total interest-earning assets were 4.80% and 4.19%, respectively. For the quarter ended March 31, 2018, overall cost of funds decreased by 3 basis points compared to the quarter ended December 31, 2017 and increased 18 basis points compared to the quarter ended March 31, 2017. Due to the continued impact of new loan growth and the runoff of higher-yielding loan balances, management anticipates continued pressure on net interest margin and net interest spread.

During the quarter ended March 31, 2018, Business First recorded a provision for loan losses of $474,000, compared to $355,000 for the quarter ended March 31, 2017. The increase in provision for the quarter ended March 31, 2018 compared to the same period in 2017 is primarily due to overall growth in the loan portfolio.

Banking Centers

As of March 31, 2018, Business First operated out of 19 offices, including 16 full-service banking centers, two loan production offices, and one wealth solutions office in markets across Louisiana and Texas.

Business First has received all the necessary regulatory approvals for converting its loan production offices in New Orleans, Louisiana and Dallas, Texas into full-service banking centers. These locations are on schedule to convert to full-service banking centers during the second quarter of 2018.

In March 2018, Business First closed a banking center in each of Zachary and Erwinville, Louisiana, which is expected to have a minimal impact on its operations and customers.

Non-GAAP Financial Measures

This press release includes certain non-GAAP financial measures intended to supplement, not substitute for, comparable GAAP measures. Reconciliations of non-GAAP financial measures to GAAP financial measures are provided at the end of the tables below.

About Business First Bancshares, Inc.

Business First Bancshares, Inc., through its banking subsidiary Business First Bank, operates 19 offices, including 16 banking centers, two loan production offices and one wealth solutions office in markets across Louisiana and Texas. Business First Bank provides commercial and personal banking, treasury management, and wealth solutions services to small to midsize businesses and their owners and employees. Visit www.b1bank.com for more information. Business First’s common stock is traded on the NASDAQ Global Select Market under the symbol “BFST.”

Special Note Regarding Forward-Looking Statements

Certain statements contained in this release may not be based on historical facts and are “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. These forward-looking statements may be identified by their reference to a future period or periods or by the use of forward-looking terminology such as “anticipate,” “believe,” “estimate,” “expect,” “may,” “might,” “will,” “would,” “could,” or "intend." We caution you not to place undue reliance on the forward-looking statements contained in this news release, in that actual results could differ materially from those indicated in such forward-looking statements as a result of a variety of factors. We undertake no obligation to update these forward-looking statements to reflect events or circumstances that occur after the date of this news release.

Additional Information

For additional information on Business First, you may obtain Business First’s reports that are filed with the Securities and Exchange Commission, or SEC, free of charge by using the SEC’s EDGAR service on the SEC’s website at www.sec.gov or by contacting the SEC for further information at 1-800-SEC-0330. Alternatively, these documents can be obtained free of charge from Business First by directing a request to: Business First Bancshares, Inc., 500 Laurel Street, Suite 100, Baton Rouge, Louisiana 70801, Attention: Corporate Secretary.

No Offer or Solicitation

This release does not constitute or form part of any offer to sell, or a solicitation of an offer to purchase, any securities of the Company. There will be no sale of securities in any jurisdiction in which such an offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of such jurisdiction.