OBJECTIVE: The objective of the study is to investigate factors related to treatment persistence among users of antihypertensive (AHT) drugs in daily practice. METHODS: Data for this study were obtained from the PHARMO database including pharmacy rcords and hospitalizations in the Netherlands (n = 950 000). Patients who newly received AHT therapy (n = 17 113) between 1997 and 2001 were selected. Of these patients, random samples of 500 patients per drug class were drawn. One-year persistence was defined as (1) the percentage of patients using AHTs at least 270 days and receiving AHT in 3 months after the 1-year follow-up period, and (2) Catalan method (Kaplan-Meier curves). Gender specific persistence rates per drug class were adjusted for significant factors including age, use of antidiabetics and lipid lowering drugs, and prior cardiovascular hospitalizations (OR and 95%CI). RESULTS: Persistence was highest in users of angiotensin II receptor blockers (ARBs) (62.0%), progressively lower in users of angiotensin converting enzyme inhibitors (ACE-inhibitors, 59.7%), betablockers (35.0%), calcium channel blockers (34.7%), and diuretics (33.0%), resulting in the highest OR of 3.4 [95%CI: 2.6-4.5] for ARBs compared to diuretics. The persistence ofAHT use in women was substantially lower (40.1% vs. 50.2%, OR 0.7 [95%CI: 0.6-0.8]) and differences between drug classes were larger than in men. CONCLUSIONS: These results demonstrate marked differences in persistence between AHT classes, with the highest persistence for ARBs and lowest for diuretics. Women were less persistent with their AHT compared to men. This low persistence leads to suboptimal treatment with a potential for substantial clinical consequences. Especially in women, more attention paid to AHT persistence patterns could improve their cardiovascular outcome. Copyright (c) 2005 John Wiley & Sons, Ltd.