Two highly polar, unconjugated metabolltes of tetrahydrocortisol and tetrahydrocortisone, which had been shown previously to account for greater than 40% of [14C]cortisol (F) administered to baboon neonates, were isolated from urine of a term newborn animal. Metabolites were extracted with ethyl acetate, purified by sequential paper chromatography and crystallization, and identified by chemical and biochemical procedures. Both metabolites of F are 5beta-pregnanes with a hydroxyl of unknown orientation at C-7, a 3alpha-hydroxyl, and a dihydroxyacetone side chain. The two compounds differ from each other by the presence of either oxo or hydroxyl functions at C-11. The following nomenclature is proposed: unknown 1: 3alpha,7xi,11beta,17,21-pentahydroxy-5beta-pregnan-20-one (7xi-hydroxytetrahydrocortisol); unknown 11: 3alpha,7xi,17,21-tetrahydroxy-5beta-pregnane-11,20-dione (7xi-hydroxytetrahydrocortisone). Production of these compounds compensates quantitatively for the decreased formation of F glucuronoside metabolites by baboon neonates, compared with that in adults. Therefore, we propose that 7-hydroxylation is a major alternative pathway for F metabolism in the perinatal period of the baboon.