Evaporative emissions of Japanese older and current vehicles (1990-1998MY) and U.S. current vehicles, which were adapted to federal regulations in 1996, were investigated using typical Japanese gasoline. Japanese older and current vehicles exhibited high levels of Running Loss (RL), Hot Soak Loss (HSL) and Diurnal Breathing Loss (DBL), and their emissions showed strong Reid vapor pressure (RVP) dependence.On the other hand, U.S. vehicles showed very weak RVP dependence, between 62kPa and 76kPa. Their emissions also showed very low levels of RL, HSL and DBL. These results suggest RVP reduction is just effective for Japanese older and current vehicles.Evaporative emissions of Japanese and U.S. vehicles were also tested according to a new Japanese test procedure and the 35 degrees centigrade RL test procedure. In the case of the RL and DBL tests, the impact of test conditions on evaporative emissions was discussed as well.