The histochemical localization of 6 lysosomal enzymes was studied in the epididymis of adult tomcats. A weak to distinct reaction for acid phosphatase, leucyl-amino-peptidase and non--specific esterase could be observed in the epithelium of the ductus epididymidis in all three segments. Among the glycosidases, N-acetyl-beta-glucosaminidase displayed the strongest activity. alpha-man and alpha-fuc could not be demonstrated. For N-Acetyl-beta-glucosaminidase, beta-Galactosidase, acid phosphatase and non-specific esterase, an increase of enzyme activity from the initial segment towards the terminal segment was seen. Intracellularly, the maximum of enzyme activity of those four enzymes was supranuclear. This histochemically enstablished pattern of enzyme activity in the epididymis of the tomcat was compared with those of other mammals. The possible functions of enzymes in the epididymis was briefly discussed.