The reproductive cycle of the male Indian palm squirrel was investigated from a collection of 365 animals during the period May 1963 to May 1965. It breeds from January to the end of July. This is followed by a period of regression (August-September) and the animals are quiescent during October and November. Redevelopment of the reproductive organs is initiated in December and results in the restoration of reproductive activity in late January. Sexual maturity in squirrels is attained by 8 to 9 months of age. The histological changes in the testis, epididymis and vas deferens with age and breeding season are described. The weights of the prostate gland and seminal vesicles show changes that parallel testicular weights and interstitial cell morphology. However, there is a time lag in the response of accessory glands both during the transition from puberal to the adult condition and in adults during the change from recrudescence to breeding condition. The role of exteroceptive factors in regulating the reproductive cycle of the palm squirrel is discussed.