To evaluate the prescription, discontinuation and switching profiles of antihypertensive agents, we studied computerized records for patients prescribed antihypertensive drugs in government primary care clinics of Hong Kong between January 2004 and June 2007, which include 1069836 antihypertensive drug visits (representing 67028 patients). The most commonly prescribed drugs were calcium channel blockers (CCBs, 49%), beta-blockers (BBs, 46%) and angiotensin-converting enzyme inhibitors (ACEIs, 19%). Although thiazide diuretic prescribing was low (13%) and on the decline (from 14% in 2004 to 12% in 2007), prescription of ACEIs was rising (from 16% in 2004 to 23% in 2007); drug discontinuation was highest for BBs (21%) and lowest for CCBs (12%) and the high rates of discontinuation in BBs remained apparent after controlling for confounders. CCBs may be particularly favourable antihypertensive drugs in Chinese and the low use of thiazide diuretics warrants further clinical and cost effectiveness studies among Chinese.