OBJECTIVES: To assess persistence to the combinations of dihydropyridine (DHP) calcium channel blockers (CCB) with an Angiotension Converting Enzyme (ACE) inhibitors or an Angiotension II Receptor Antagonist (A2RA), using PBS claims data provided by Medicare Australia. METHODS: This analysis is based on all scripts supplied to a one in ten sample of the Australian population drawn from de-identified Pharmaceutical Benefits payment records from January 2003 to December 2006. Initiation occurred with 2 consecutive months of an A2RA or an ACE combined with a DHP following at least 6 months without a DHP combination.  Treatment cessation was 3 consecutive months of none or just one of the drugs making up the combination. Hazard ratios (HR) were derived and adjusted for patient age/ sex and initiating speciality.  RESULTS: More than 17,500 Concessional patients, initiated on a DHP combined with an A2RA and more than 12,000 Concessional patients, initiated on a DHP combined with an ACE, had their persistence to the combination assessed.  Median persistence [95% CI] differed between DHP combinations:  Lercanidipine/A2RA 23 months [22-25], Felodipine/A2RA 20 months [18-22], Nifedipine/A2RA 17 months [16-18], and Amlodipine/A2RA 14 months [13-15].  Using Lercanidipine/A2RA as the reference (HR = 1.00), patients were significantly more likely to cease the other combinations Felodipine/A2RA (8.7%), Nifedipine/A2RA (18.5%) and Amlodipine/A2RA (33.9%). Lercanidipine/ACE 24 months [22-26], felodipine/ACE 21 months [19-24], nifedipine/ACE 16 months [14-18], and amlodipine/ACE 15 months [14-17].  Using Lercanidipine/ACE as the reference (HR = 1.00), patients were more likely to cease the other combinations felodipine/ACE (7.2%), nifedipine/ACE (26.5%) and amlodipine/ACE (28.6%). CONCLUSIONS: In terms of optimal treatment persistence, lercanidipine seems to be the best DHP to combine with an A2RA or an ACE, while amlodipine seems to be the worst DHP to combine with an A2RA or an ACE.