Abstract: Male rats were given gossypol acetic acid by mouth at a daily dosage of 10 mg/kg six days a week for six months. At the end of this period the main viscera were removed for pathological examinations. The chemical substances and enzymes in the adrenal glands, kidneys and livers were demonstrated by histochemical methods.Results showed that after six month treatment with gossypol acetic acid, no pathological changes were found under the light microscope in the heart, liver, spleen, lung, kidney, intestine, lymph node, bone marrow and blood picture.The 3 β-hydroxysteroid-dehydrogenase in the zona glomerulosa of the adrenal gland of the treated group was of slightly higher intensity which might indicate slightly higher enzyme activity. Oil red "O" and Sudan Black B stained specimens showed either slight increase or slight decrease in the number of fat droplets in the zona glomerulosa of the gossypol treated as compared with the control animals. No changein the renal G-6-PDH and renal ATPase activities was noted in the treated animals. The acid phosphatase activity of the proximal and distal tubules of the treated animals seemed to be slightly increased and the alkaline phosphatase activity of the proximal tubules showed very little changes. No variation from controls was observed in the ATPase, alkaline phosphatase and acid phosphatase activities of the liver. Liver glycogen, G-6-Pase and RNA did not differ from that of controls besides that there are some changes in a few cells. However, the G-6-PDH activity of the liver seemed to be slightly increased in gossypol treated rats.Liver glycogen contents as determined by the method of Van der Vies showed no significant difference between the control and gossypol treated animals.