In clinical trials alcohol brief intervention (BI) in adult primary care has been efficacious in reducing alcohol consumption, but we know little about its impact on health outcomes. Hypertension is a prevalent and costly chronic condition in the U.S. and worldwide, and alcohol use is a modifiable hypertension risk factor. To evaluate the effect of receiving BI for unhealthy drinking on blood pressure (BP) control among adult hypertensive patients by analyzing secondary data from a clustered, randomized controlled trial on alcohol screening, brief intervention and referral to treatment (SBIRT) implementation by primary care physicians (PCP intervention arm) and non-physician providers and medical assistants (NPP&MA intervention arm) in a large, integrated health care delivery system. Observational, prospective cohort study. 3811 adult hypertensive primary care patients screening positive for past-year heavy drinking at baseline, of which 1422 (37%) had an electronic health record BP measure at baseline and 18-month follow-up. Change in BP and controlled BP (systolic/diastolic BP <140/90mmHg). Overall no significant associations were found between alcohol BI and BP change at 18-month follow-up when analyzing the combined sample of subjects in both intervention arms. However, moderation analyses found that receiving BI for positive past-year unhealthy drinking was positively associated with better BP control at 18months in the PCP intervention arm, and for those with lower heavy drinking frequency and poor BP control at the index screening. Our findings suggest that hypertensive patients may benefit from receiving physician brief intervention for unhealthy alcohol use in primary care. Findings also highlight potential population-level benefits of alcohol BI if widely applied, suggesting a need for the development of innovative strategies to facilitate SBIRT delivery in primary care settings.