The non-protein (NP-SH), total (T-SH) and protein bound sulfhydryl groups (PB-SH) were measured in the thyroid, adrenals, kidney, liver and skeletal muscle of hypophysectomized and sham operated adult male rats. After hypophysectomy, T-SH and PB-SH in the adrenals and thyroid decreased significantly (P less than 0.01). The maximal decline occurred at the intervals of 12-24 days after hypophysectomy. The NP-SH fraction, which is represented mainly by SH-glutathione, decreased within 24 h after hypophysectomy in both glands, then increased transiently and later it again decreased in parallel to the level of both T-SH and PB-SH. In the kidney, all fractions of SH groups increased at 4--8 days, then decreased markedly reaching control or even subcontrol levels. In contrast, we failed to observe hypophysectomy induced changes of any of the SH-fractions in the liver and muscle of rats.