OBJECTIVES: Hypertension (HTN) is an important and prevalent risk factor for cardiovascular diseases. In Taiwan, the prevalence of hypertension is around 21.4% and only about 40% patients with acceptable range of blood pressure control. The purpose of this study is to evaluate the trend of anti-hypertensive medications and also examine the risk of stroke among these HTN patients from 2001 to 2004 in Taiwan. METHODS: Based on the National Health Insurance (NHI) database, there are 1,931,436 patients with ICD-9 coding of hypertension, we randomly selected 10% hypertension outpatients (194,547 subjects) from the NHI claim database, after excluded those visited less than 3 times or without anti-HTN medication, 135,660 patients in the finally analyses. These subjects follow their anti-HTN medications and occurrence of stroke for a 4-year  period. RESULTS: Among these patients, 27.6% used only one medication and 37.0% with 3 or more medications for HTN. There are 9530 (4402 males and 5128 females) patients had both drug information on 2001 and 2004. The prevalence of stoke was 7.3% in 2001 and increased to 13.6% in 2004. The average out-patient medical costs for hypertension were increased from NT$15,778.7 to 19,712.1 dollars (at an exchange rate of 32 NT$ to 1 US$) from 2001 to 2004.  Using Cox proportion hazard model, gender (male) and age were important factors to predict the occurrence of stroke. Comparing with beta-blocker, diuretics had higher relative risk for stoke but the risk was attenuate after adjusted for other confounders (HR = 1.3, 95% CI 0.7 – 2.6). CONCLUSIONS: From this study, the out-patient medical costs for hypertension were increased from 2001 to 2004 in Taiwan. However, the occurrence of stroke among hypertensive patients was also increased during this period. There was no significant protective effect for stroke among hypertensive patients using different anti-HTN medications. Further studies may be indicated to evaluate the cost-effectiveness of different medications on hypertensive-related disorders.