The proclamation of April 2002 of a Ministry of Health, Labor and Welfare ordinance has enabled doctors to prescribe drugs for an outpatient without a limit on the length of prescription terms except for a few drugs. There is a concern that the prescription-term deregulation could cause careless drug therapy management in order to extend the interval between patient hospital visits. The purpose of this study is to make pre- and post-deregulation comparisons of two items, prescription terms and implementation of clinical examination that complied with package-insert precautions, and to discuss the approaches to increase safety. Prescription terms have lengthened progressively. In the pre-regulation period of January to March 2002, the mean prescription term was 19.9 days; in the post-regulation period of July to September 2002, it was 24.9 days; and in July to September 2003, 28.6 days. Even for anti-tumor agents, there were prescriptions over 90 days after deregulation. There was no significant difference between the pre- and post-deregulation compliance ratios for the package-insert precautions in eight drugs of investigated nine. However, one case had a delay in detection of liver dysfunction, which was caused by deviation from the once-a-month testing indicated in the package-insert precautions for prolonged prescription terms. The evidence suggested that the deregulation led to negligent drug therapy management. To assure safe therapy, the following should be addressed: first, sufficient function of a computerized prescriber order entry system and second, creation of a new framework with pharmacists' active involvement such as collaborative therapy management with physicians.