Human organic lesions, which were induced by narcotic poisons, are caused by application and directly or indirectly by toxic substances. Cause of death is very often edema of the lung and the brain or toxic circulatory failure as well as an insufficiency of organic functions by cellular degeneration. Users of narcotic poisons mainly show liver damage. Cell degeneration and infiltration of round cells in the portal-biliary areas are mostly interpreted as drug hepatopathy and not as viral hepatitis. Enzyme levels in histochemical reactions are decreased in the damaged liver tissue. The kidneys show toxic degeneration and inflammatory reactions. Brain lesions are confined to cellular damage, without necrotic degeneration of larger areas. Sporadically perivascular hemorrhages are seen. Heart and vascular system mainly show an inflammatory reaction caused by the application of the poison and seldom embolism in the capillaries by injection of dissolved tablets. Centrally stimulating substances cause hypertrophy of the tunica media in the lung vessels, combined with pulmonary hypertension.