OBJECTIVE: To assess the proportion of patients starting with antihypertensive drug treatment who continued treatment for at least 10 years. DESIGN: A retrospective cohort study. SETTING: The PHARMO record linkage system containing drug dispensingecords from community pharmacies and linked hospital discharge records of approximately 950 000 subjects. PARTICIPANTS: Patients who started using antihypertensive drugs (two or more prescriptions) in 1992 and did not receive a prescription for any antihypertensive drug in the 365 days preceding the first prescription. MAIN OUTCOME MEASURE: Persistence with antihypertensive drugs until 10 years. RESULTS: Among a total of 2325 patients who started using antihypertensive drugs, 39% used continuously during the 10 years of follow-up. Approximately 22% temporarily discontinued and restarted treatment, whereas 39% of patients discontinued permanently. Older patients were more persistent than younger patients [20-39 years: odds ratio (OR) 2.08; 95% confidence interval (CI) 1.52-2.84; 40-59 years: (reference), >/= 60 years: OR 0.69; 95% CI 0.54-0.89]. More patients who started with diuretics (reference) and beta blockers (OR 1.15; 95% CI 0.87-1.52) discontinued compared with those who started with dihydropyridine calcium antagonists (OR 0.54; 95% CI 0.34-0.84), and angiotensin-converting enzyme (ACE) inhibitors (OR 0.38; 95% CI 0.27-0.55). Patients who started with combination therapy (OR 0.29; 95% CI 0.14-0.54 compared with diuretics) or patients who wereinitially treated by a cardiologist (OR 0.82; 95% CI 0.61-0.97) or internist (OR 0.80; 95% CI 0.62-0.98 compared with general practitioners) also showed higher persistence. CONCLUSION: Long-term persistence in daily practice is low compared with persistence observed in randomized clinical trials and should be considered in the choice of a first-line antihypertensive agent.