The annual reproductive changes in the testes and epididymis of the soft-furred field rat,Millardia meltada have been investigated. The males of this species are sexually quiescent between January and April. Two peaks of highest reproductive activity occur annually in October and December. Interstitial cells show seasonal activity which approximately parallels the condition of the testes and epididymis. A correlation of these changes with the environmental conditions during 1977–78 indicates that the lowest temperature, shortest daylength and natural conditions occurring after the rainfall are congenial for reproduction of this species.