OBJECTIVES: To examine the effect of a brief pharmacist telephone intervention on adherence to ACE-Is/ARBs among non-adherent hypertensive patients with diabetes enrolled in a Texas-based Medicare Advantage plan. METHODS: The health plan medical claims data was used to identify patients with hypertension and diabetes diagnoses and at least 2 fills for ACE-Is or ARBs between January/2013-October/2013. Patients who failed to refill their medication for more than one day, and had a proportion of days covered (PDC) <0.8 were considered non-adherent and contacted by a pharmacist by phone. Descriptive statistics were conducted to assess the frequency distribution of sample demographic characteristics at baseline. A multiple linear regression was conducted to assess the intervention effect on adherence during the 6 months post-intervention. The outcome variable was 6-month post intervention PDC. Other control variables included were baseline PDC, demographics, physician specialty (primary care vs. specialist), health plan (low income subsidy vs. not), CMS Risk Score, Charlson comorbidity index and number of other medications. RESULTS: A total of 131 patients were included in the analysis with 66 in the intervention group. The mean post intervention PDC  for the intervention group was 0.58 (SD±0.26) and 0.29 (SD±0.17) for the control group. Intervention was a significant predictor of better adherence in the linear regression model after adjusting for all the other baseline covariates (β=0.318, p<0.001), but the post intervention PDC was still lower than the generally accepted PDC of 0.8. Other covariates were not statistically significant. CONCLUSIONS: The brief pharmacist telephone intervention resulted in significantly better PDCs during the 6 months following the intervention but the overall PDC rates in both the intervention and control groups remained low. Future research should investigate the impact of behavior modifications which incorporate motivational interviewing and determine if this leads to a sustainable behavioral change and improved adherence.