OBJECTIVES: This analysis examines persistence and compliance with the most commonly used cardiovascular drug classes among seniors to assess the degree to which these drugs are being used as prescribed. METHODS: This study uses drug claims data from the National Prescription Drug Utilization Information System (NPDUIS) database, housed at the Canadian Institute for Health Information. The database contains claims for roughly 70% of Canadian seniors. Persistence was measured by the amount of time a drug class was used before the presence of a gap in drug therapy that exceeded a pre-determined number of days. Compliance was measured by the proportion of days covered (PDC), calculated by summing the days’ supply for a senior taking a single drug class over a one-year period. RESULTS: