This study is based upon the postmortem findings in 328 cases of rhesus monkeys which were bred in our institute from 1991 to 1997. The statistics indicated that the highest mortality was respiratory system disease, the ratio was 39.6%, the mortality of digestion system and syndrome disease was 27.1% and 14.0% respectively. The high mortality period of monkeys was from January to April in the institute, the death ratio is 43.4% of whole year during that period. The death ratio of male was (64.2%) higher than that of female (35.8%) in infant group, which was 56.6% of males and 43.4% of females in juvenile group, but which of males was (26.6%) lower than that of females (73.4%) in adult group. In this paper we describe and analyse the pathological and clinical material concerning the observation, diagnosis, treatment and prevention disease of rhesus monkey from breeding the environment.