BACKGROUND: Adherence to medication regimens is poor in the management of chronic diseases, including asthma. OBJECTIVE: To determine whether an audiovisual reminder device improves adherence with inhaled corticosteroid (ICS) therapy in adult asthma. METHODS: A randomized open-label parallel group study of 110 adult or adolescent subjects with asthma was undertaken. Subjects were randomized to receive 24 weeks of fluticasone propionate 250 microg, 1 actuation twice daily via a metered dose inhaler (MDI) with or without an audiovisual reminder function (AVRF). All MDIs had electronic covert adherence monitors. The primary outcome variable was adherence, defined as the proportion of medication taken as prescribed over the final 12 weeks of the study. Adherence was also assessed as the proportion of subjects who took >50%, >80%, or >90% of prescribed medication. RESULTS: The proportion of medication taken in the last 12 weeks was greater in the AVRF group (93%) compared with the control group (74%), with a difference of 18% (95% confidence interval [CI] 10-26%; P < .0001). The proportion of subjects taking >50%, >80%, or >90% of their medication was greater in the AVRF group, with a ratio of proportions adherent of 1.33 (95% CI, 1.10-1.61; P = .003), 2.27 (95% CI, 1.56-3.3; P < .0001), and 3.25 (95% CI, 1.74-6.1%; P < .0001), respectively. CONCLUSION: An audiovisual reminder function can significantly improve adherence with ICS therapy in adult asthma. CLINICAL IMPLICATIONS: An audiovisual reminder function has potential to improve adherence with medication regimens across a wide spectrum of diseases, in both research and clinical practice.