The metabolism of cortisol-21-glucosiduronate has been studied in two subjects. Urinary excretion was about 65% in both subjects, with cortisol glucosiduronate as the principal metabolite accompanied by small amounts of 11 beta, 17,21-trihydroxypregnane-3,20-dione (THF) glucosiduronate. The absence of the other normal metabolites of cortisol [17,21-dihydroxypregnane-3,11-20-trione (THE), 3 alpha, 11 beta, 17, 20xi, 21-pentahydroxypregnane, and 3 alpha, 17, 20xi, 21-tetrahydroxypregnan-11-one] indicates that negligible hydrolysis at C-21 occurred and that an unoccupied C21 position is required for oxidation at C-11 and reduction at C-20. The limited conversion to THF suggests that a pathway through cortisol-21-glucosiduronate does not contribute significantly to the differences in specific activity of urinary THF and THE observed after administration of labeled cortisol.