Objectives: Several practice guidelines recommended both medication and behavior modification to control hypertension. The objective of this study was to analyze ambulatory care utilization pattern and related factors. Methods: A retrospective cohort study was conducted among 45,267 new users who initiated treatment with hypertensive drugs in 2003. Korean National Health Insurance Claims Data was used to study the medical care utilization behavior and related factors after treatment initiation for up to four years. Taking prescription was considered as medical care utilization. Results: More than 20% of patients discontinued visiting physicians for prescription after initiating antihypertensive drug therapy. The average number of institutions visited by patients was about 1.3 annually. Clinic was the most frequently visited institution by patients. In GEE analysis, probability of continuous visit one institution after initiating antihypertensive drug treatment increased in patients who were women, old, have comorbidity, visited clinic or hospital mainly in previous year. Conclusions: Young hypertensive male patients who have no major comorbidity showed high possibility to discontinue medical service utilization. It is necessary to educate these targeted patients about importance of hypertension management in early stage after treatment initiation.