OBJECTIVES: A business hours study by pharmacy practice was examined as a part of patient safety activities associated with hospital pharmacy. METHODS: We surveyed nationwide the situation of patient safety activities in hospitals allowed for additional costs on patient safety measures under the social insurance medical fee schedule. Of targeted 2674 hospitals (all hospitals: 8706 as of June 1) in Japan, 669 hospitals responded (response rate: 25.0%). Pharmacy practice includes medication teaching and history administration, brought drugs review on admission, drug adjustment and dispense, question reference from out-of-hospital pharmacy, drug information for safety use. RESULTS: We classified 669 hospitals into three classes; additional cost I (85 points) implementing hospitals with more than 401 beds (A group: 173 hospitals), additional cost I (85 points) implementing additional cost I with less than 400 beds (B group: 306 hospitals), and additional cost II (35 points) implementing hospitals (C group: 180 hospitals). The time spent for medication teaching and history administration was 20.6% of all pharmacy practices in A group, 20.4% in B group, and 18.1% in C group. Similarly, the time for brought drugs review was 6.6% in A group, 8.2% in B, and 7.5% in C, and the time for drug adjustment and dispense of anti-neoplastic drugs was 9.4% in A, 5.9% in B, and 1.9% in C. The time for question reference from out-of-hospital pharmacy was 2.9% in A, 4.3% in B, and 4.6% in C. CONCLUSIONS: The time for medication teaching and history administration, and drug adjustment and dispense of neo-plastic drug and IVH were spent much more time at large scale hospitals like A group hospitals than at small scale hospitals like C group hospitals.