OBJECTIVES: To demonstrate the impact of staff pharmacists of interventions at a large (2389 beds), tertiary care teaching hospital in Southern Taiwan. METHODS: Based on the self-reported documentation made by pharmacists during the conduct of routine dispensing activities in ambulatory and inpatient setting. Those intervened suggestions were accepted by prescribing physicians. A peer-review team decided the potential clinical significance of the self-reported documentation, and assessed their cost savings results. Data collection period was from January 1 to December 31, 2001. RESULTS: A total of 4424 interventions (94.8% of reported documentations) by 25 pharmacists were analyzed. Of which, 59.4% of these interventions were found to affect inappropriate prescribing, 35.4% of these interventions were associated with inappropriate drug utilization and the remaining 5.2% of interventions were drug interactions and miscellaneousness. Six percent of reported documents were evaluated in terms of direct cost savings (the difference in actual acquisition costs between prescriptions). Cost savings were over $7400 and average $27 per intervention for those sampled data. The most cost-saving interventions were related to incorrect quantity with the indication, no indication, and improper concomitants/duplication. CONCLUSIONS: The self-report documentation tool in this constitute confirms the potential to minimize the risks, cost saving and to improve hospital prescribing associated with drug therapy.