This proposal is aiming at reducing the numbers of prescription revision in out-patient department (OPD). In responding to the surveillance of Department of Pharmacy with reports that the error rate of prescription regimen in OPD is higher than expected, we collect these events from all the OPD during Aug 1, 2004 to Jan 31, 2005, and there were in average 89 events per month. Even though the number of these error events is not so many, it is still noteworthy to pay attention to in respect to the drug safety of our patients. After analyzing the causes, the possible factors include: mistakes in operating the computer for prescription by the OPD personnel; lack of hints in computer information system to discriminating the multiple dosage regimens of a single drug or to offer the possible drug interaction; repeated prescription; similarity in drug name; mistakes in the days for drugs prescribed or poor-preparations of common-used regimen as a panel. We set out the improve ment for these factors by (1) revising the standard operation system for keying in prescription regimen in OPD; (2) making the drug regimens which were common used in each specific OPD; (3) cooperating with Department of Informatics for establishing the drug-safety network; (4) implementing the OPD nursing staffs by regular continuous education activities, with the final target to reducing the error number of prescription events below 50 per month. After performing these strategies for consecutive 3 months, the revised numbers of prescription in OPD was reduced from 89 to 42 per month, which achieved the target of this proposal. The results demonstrated that this proposal is actually working and effective.