OBJECTIVES: Therapeutic interchange is not a well-accepted clinical practice in the medical society in Asia.  Clinic blood pressure readings, patients’ tolerance, and cost-effectiveness were used as measures to evaluate the impact of a therapeutic interchange program implemented at a medical center in Taiwan. METHODS: Taipei Medical University-Wan Fang Medical Center initiated a therapeutic interchange program involving angiotensin II receptor blockers (ARBs). Data were retrospectively collected for 444 hypertensive outpatients who were converted from other ARBs to candesartan.  Evaluation of therapeutic efficacy, adverse effects associated with therapy, and drug costs was conducted before and after the program implementation. RESULTS: Patients who were converted to candesartan experienced no statistically significant differences in blood pressure, and the average number of antihypertensive agents used per patient remained unchanged.  A direct cost savings of US$ 62,237 was estimated for the 444 patients studied, which amounted to a savings of more than US$ 730,000 annually for all outpatients using ARBs.  Only 3.15% of patients developed ADRs potentially related to the candesartan and none required hospitalization. CONCLUSIONS: Based on the results of this retrospective chart review, the present therapeutic interchange program was successfully developed and implemented.  This is the first study to establish the positive impact of a well-run ARBs therapeutic interchange program in Taiwan.