Age-related changes in pharmacokinetics and pharmacodynamics of drugs, in functional reserve of target organs, and in tumor biology, may lessen the benefits and enhance the toxicity of cancer chemotherapy. These changes include progressive decline in glomerular filtration rate, enhanced risk and severity of mucositis and peripheral neuropathy, and increased incidence of refractory forms of acute myeloid leukemia. Myelotoxicity is also increased following aggressive combinations of cytotoxic drugs. While hormonal therapy is well tolerated, biological treatment with recombinant alpha interferon at doses higher than 5mU/daily may be associated with acute demential syndromes in persons over 65. Tolerance of treatment may be improved by selecting alternative, safer drugs, antidotes to drug toxicity, and adjusting schedule and route of drug administration. A major advancement in supportive care has been the synthesis of hemopoietic growth factors, which are effective even in patients of advanced age.