The activities of several glycosidases in the lysosomal fraction of the uterine endometrium of rabbit were measured using 4-MU-glycosides as substrates. The specific activity of beta-N-acetylglucosaminidase was the highest, which was followed by beta-galactosidase, beta-glucuronidase, and alpha-galactosidase in this order. beta-Glucosidase had the lowest activity among the glycosidases examined. In order to examine the hormonal effects on these glycosidases, the lysosomal fractions were prepared from the uterine endometrium of the control, estrogen-treated, and progesterone-treated rabbits. In all glycosidases examined, except for beta-glucosidase, the specific activity was highest in the lysosome obtained from estrogen-treated rabbit. The specific activity in the lysosome from the progesterone-treated rabbit was between that from the estrogen-treated rabbit and that from control. Hormonal treatments, however, affected neither pH optimum curves nor isozyme patterns of these glycosidases.