AIM: To understand the capacity of fetal adrenal to catalyze reaction metabolites. METHODS: Subcellular fractions were prepared by differential centrifugation in fetal adrenal and liver. Glutathione (GSH)-transferase, reductase, and peroxidase were measured. RESULTS: The mean values (mu mol.min(-1)/g protein) of GSH-transferase activities in adrenal microsome (112 +/- 34), mitochondria (62 +/- 5), and cytosol (191 +/- 89) were 373 %, 270 %, and 167 %, respectively, higher than those in the corresponding fractions of fetal liver. Adrenal microsomal GSH-transferase was positively correlated with adrenal microsomal P-450 (r = 0.821, P < 0.01), and with adrenal microsomal aminopyrine N-demethylase (r = 0.829, P < 0.01). The GSH reductase contents (mu mol.min(-1)/g protein) in adrenal mitochondria (24 +/- 14), and in S-9 (36 +/- 15) were almost 5 times higher, compared with that in liver. Selenium-dependent GSH peroxidase was present in all the adrenal. CONCLUSION: Fetal adrenal, with greater capacities than those of liver in detoxifying reaction, may act as a drug-metabolizing organ during development.