Skin necrosis is a rare complication of heparin administration that is usually localized to injection sites. A 32-year-old insulin-dependent diabetic patient, receiving intravenous (IV) and low-dose heparin sodium therapy, had cutaneous necrosis in areas distant to the sites of injection. Prior to the onset of cutaneous lesions, thrombocytopenia develop]ed in the patient that may have been heparin induced. Heparin may induce the production of platelet aggregating immunoglobulins that predispose persons who are sensitive to the drug to thrombocytopenia, skin necrosis, and thrombotic events. Obesity, diabetes, and treatment with broad-spectrum antibiotics seem to increase the risk of such complications. Cutaneous necrosis secondary to heparin administration may serve as a warning of the potentially lethal complications of IV use. In patients in whom skin necrosis or thrombocytopenia develops, heparin therapy should be discontinued and anticoagulation with an oral agent should be considered.