A histochemical investigation was carried out after Gomori's method on the activity and localization of the alkaline and acid phosphatase in the testis and epididymis of 28 calves of the Black-and-white breed as dependent on their age--from the first day following birth to the age of 12 months, divided into 14 test groups. It was found that both enzymes had analogous localization in the testis as well as in the various portions of the epididymis, however, the activity of the alkaline phosphatase was higher as compared to that of the acid phosphatase. While in the interstitium of the testis and epididymis on the 1st, 15th, and 30th day following birth the alkaline phosphatase had low activity the acid phosphatase on the same dates was found in the epididymis only.