The Japanese Good Laboratory Practice (GLP) Standard on Drugs was finalized as a guideline and implemented in April, 1983. This standard is intended to ensure the quality and integrity of the data from nonclinical toxicity studies submitted to the Ministry of Health and Welfare in support of applications for approval to manufacture or import new drugs or to be used in the reevaluation of previously approved drugs. The standard includes a guideline for organizational matters, personnel, facility, equipment, testing operation, documentation and conduct of studies. Principles and influences of implementation of Japanese GLP will be discussed briefly in comparison with foreign GLPs.