Cytotoxic drugs, which are widely used as immunosuppressive and antiinflammatory agents in patients with neoplastic conditions, and cancer chemotherapy preparations, are of long-range concern due to the problem of cumulative organ toxicity which is not manifested until damage is extensive. These considerations have arisen because of their widespread use in recent years. Those involved in hepatic toxicity are the antimetabolites methotrexate and 6-mercaptopurine. Bisulfin, bleomycin, and methotrexate have been linked to pulmonary toxicity. Daunomycin and adriamycin, used as anticarcinogens, are examined for their cardiac toxicity. Cyclophosphamide and streptozotocin affect the urinary tract. These drugs have specific toxic effects on fertility in both males, through its disruption of the testicular function, and in females, for ovarian disruptions. Antifolics, 6-mercaptopurine, azathioprine, and alkylating agents, used for therapy in pregnant women, particularly in the first 4 months, are linked to the appearance of fetal abnormalities. The process of carcinogenesis is examined for clues to possible chemotherapy-related 2nd tumors, which appear during the course of treatment.