OBJECTIVES: To investigate if there are differences in the persistence and compliance to therapy depending on the antihypertensive drug class prescribed first (index drug). METHODS: Prescription claims data were analysed for the 2000 to 2003 time period. Index prescriptions were determined for: ACE-inhibitors (ACEi), angiotensin receptor blockers (ARB), beta blockers (BETA), calcium channel blockers (CCB), and diuretics (DIU). Patients regarded as newly diagnosed (i.e., without any antihypertensive medication 180 days before the index time point) with a follow-up of at least 360 days were included in the study. Persistence rates (percentage of beneficiaries on continuous therapy with the index drug at 180 and 360 days) were calculated for each drug class. Compliance was determined in terms of the medication possession ratio (MPR) for 180 and 360 days (dispensed supply in defined daily dose (DDD) within 180 and 360 days divided by the total number of days). RESULTS: Most of the 62,754 beneficiaries had an index prescription of BETA, followed by ACEi, DIU, CCB, and ARB. Persistence rates at 180 and 360 days were highest for ARB (71.0 and 52.7%, valsartan 77.1 and 59.3%), followed by CCB (51.5 and 34.4%), ACEi (50.2 and 34.5%), DIU (41.3 and 26.0%), and BETA (25.1 and 13.6%). After adjusting for age, sex, and diabetic comorbidity, the persistence remained significantly higher for ARB compared to all other drug classes. The MPR for 180 and 360 days showed a similar pattern with the highest ratio for ARB (0.88 and 0.84; valsartan 0.92 and 0.87), followed by CCB (0.73 and 0.66), ACEi (0.72 and 0.67), DIU (0.70 and 0.63), and BETA (0.51 and 0.45). CONCLUSION: ARBs, and valsartan as a representative of the class, showed the highest persistence and compliance suggesting that a more sustained blood pressure control could be expected from utilization of ARBs and Valsartan.