Modalities of cancer treatment are among the most toxic treatments. Therefore, the efficacy of anticancer therapy is always accompanied by the risks of side-effects for the normal tissue. The frequency of diferent organ dysfunctions and insufficiency grows with aging, which increases even further the risk for treatment related side-effects. Both renal and liver insufficiency complicate the provision of chemotherapy and targeted therapy in the elderly. Despite this, even in this subgroup of cancer patients, effective medical therapy is possible. The latter, however, requires thorough assessment of organ function before planned therapy, adequate treatment of other non-cancerous diseases and dose modifications whenever these are deemed necessary.