The objective of this study was to evaluate the effectiveness of an automated telephone system reminding patients with hypertension and/or cardiovascular disease to obtain overdue medication refills. The authors compared the intervention with usual care among patients with an overdue prescription for a statin or lisinopril-hydrochlorothiazide (lisinopril-HCTZ). The primary outcome was refill rate at 2 weeks. Secondary outcomes included time to refill and change in low-density lipoprotein cholesterol and blood pressure. Significantly more patients who received a reminder call refilled their prescription compared with the usual-care group (statin cohort: 30.3% vs 24.9% [P<.0001]; lisinopril-HCTZ cohort: 30.7% vs 24.2% [P<.0001]). The median time to refill was shorter in patients receiving the reminder call (statin cohort: 29 vs 36 days [P<.0001]; lisinopril-HCTZ cohort: 24 vs 31 days [P<.0001]). There were no statistically significant differences in mean low-density lipoprotein cholesterol and blood pressure. These findings suggest the need for interventions that have a longer-term impact.