This study is tried to suggest the new model to shorten the patient's waiting time from counting department to receiving drugs from pharmacy after doctor's diagnosis. The method of this study is designed to simulate from counting time to finishing time of dispensing drugs for internal medicine outpatients. The results are as follows : First, the increasing the numbers of server at pharmacy and counting department in present model don't effect on shortening outpatient's waiting time. Second, in the case of application of OCS, the outpatient's waiting time for receiving dispensed drugs from pharmacy is rather delayed because of no waiting time for counting. Third, in the case of application OCS and ATC simultaneously, the outpatient's waiting time for receiving dispensed drugs is shortened, and in this case, the increasing the numbers of server at pharmacy effect more greatly on the changes of patient's waiting time for receiving dispensed drugs from pharmacy. From the results of this study, it is noted that the best optimal for shortening outpatient's waiting time in general hospital is to introduce the OCS and ATC simultaneously in the process between the counting department and pharmacy, and increasing the numbers of server at pharmacy.