The working group for reevaluation of the Guideline for General Pharmacology Studies has completed a draft guideline for Safety Pharmacology studies and plan to recommend replacing the existing guideline with the revised one. This proposed guideline is now subject to domestic and international consultation. The basic principle of the revision is to harmonize the guideline with the international concepts. The working group decided to change the title of “General pharmacology” to “Safety pharmacology”, because the objective of this guideline is to assess the safety of a test substance in humans by examining the pharmacodynamic properties of the substance. The proposed guideline includes studies on vital functions as essential studies that should be performed prior to human exposure. Studies are also required to be conducted when predictable or unexpected observed effects are concerned. The working group recommends a case-by-case approach to select the necessary test items in consideration of the variable information available.