Comparison of the data provided by the passive epidemic reporting system (PERS) with those of epidemicologic investigation during the outbreak of measles in a rural area, Rongshui County, from November 26, 1992 to May 10, 1993 indicated that the PERS delayed the report one month during the outbreak, failed to describe the time, place and age distributions correctly. The main drawbacks of the PERS were tediousness and delay. The reformed active surveillance system with diagnostic recipe made the reporting precedures much simpler and well acceptable by the physicians.