Exhibit 15.1

Consent of Independent Registered Public Accounting Firm

The Board of Directors of Acasti Pharma Inc.

We consent to the incorporation by reference in the registration statements on Form S-8 (No. 333-191383 and No. 333-227476), and Form F-3 (No. 333-223464) of Acasti Pharma Inc. of our report dated June 26, 2019, with respect to the statements of financial position as at March 31, 2019 and 2018, the related statements of earnings and comprehensive loss, changes in equity and cash flows for the years ended March 31, 2019 and 2018 and the thirteen month period ended March 31, 2017, and the related notes, which report appears in the annual report on Form 20-F of Acasti Pharma Inc. dated June 26, 2019.

Our report dated June 26, 2019 contains an explanatory paragraph that states that Acasti Pharma Inc. has incurred operating losses and negative cash flows from operations since inception and additional funds will be needed in the future for activities necessary to prepare for commercial launch, which indicate that a material uncertainty exists that casts substantial doubt about its ability to continue as a going concern. The financial statements do not include any adjustments that may be necessary if the going concern basis was not appropriate.

Our report dated June 26, 2019 also contains an explanatory paragraph that states that the financial statements of Acasti Pharma Inc. for the twelve-month and one-month periods ended February 28, 2017 and March 31, 2017 respectively are unaudited. Accordingly, we do not express an opinion on them.

June 26, 2019

Montréal, Canada