Abstract
The post mortem examination of 158 Mongolian gerbils (80 males and 78 females) revealed that 61 cases (38.6%) of them carried spontaneous neoplasms [22/80 (27.5%) of males and 39/78 (50%) of females] . In the male, sebaceous gland carcinoma at the abdominal skin was observed in 18/22 (81.8%) of tumor cases. In the female, granulosa cell tumor was seen in 31/39 (79.4%) of tumor cases. These two tumor types were markedly predominant in gerbils older than 3 years. The each incidence of other types of tumor was less than 5% in male and female animals.