This study is aimed to pursue a possible introduction of a unit-of-use packaging for prescription drugs to Japan. The survey of pharmacists’ opinions about a unit-of-use packaging was also carried out. In addition, prescription days found in 77,212 prescriptions were related to daily number of times to take medicine, medicinal effects and medical institutions that issued prescriptions in question. The percentage of prescription days with a multiple of 28 days was 24.6％ and that with 30 days was 18.2％. If the group medical institutions which prescribe mainly for 30 days change the main prescription days from 30 days to 28 days, 42.8% of prescriptions could be dispensed without opening packages for 28 days. In this case, the percentage could be increased in drugs for chronic diseases. According to the survey for pharmacists, 34.6% prefer unit-of-use packaging, 24.8% prefer bulk packaging and 40.5% showed no preference. The reasons for preferring unit-of-use package were “reduction of dispensing time” 94.3% and “prevention of dispensing errors” 73.6%. 90.8% of the pharmacists indicated that various prescription days is the main factor for a limited introduction of unit-of-use package to Japan. It was concluded that the key issues to be considered for acceleration of introduction of unit-of-use packages for prescription drugs in Japan are the following: 1) maximum unification of prescription days to 28 days instead of 30 days, 2) start with drugs for chronic diseases, 3) preparation of 28-day packages, and 4) start with drugs taken once a day.
