Enzyme histo-cytochemical staining including alkaline phosphatase, acid phosphatase and 3 beta ol dehydrogenase in human fetal adrenal glands (13 to 20 week fetuses) was studied. Enzyme histo-chemical activity of alkaline phosphatase was mainly observed in cell membranes of the fetal cortex. The permanent cortex showed weak or negative activity. Histochemical staining of acid phosphatase was mostly observed in the cytoplasm as large globular structures near the nucleus in the fetal cortex, and intracellular localization of acid phosphatase by electron microscopic enzyme cytochemistry was mainly observed in lysosomes including dense bodies of the fetal cortex. The permanent cortex was only slightly stained for acid phosphatase. The activity of 3 beta ol dehydrogenase was predominantly observed in the cytoplasm of the fetal cortex in the 20 week fetus. Based on these findings, the significance of these enzymes in the fetal cortex is discussed.