Heparin-induced thrombocytopenia is a common and clinically important drug-induced complication that can cause life- and limbthreatening thrombosis. Epidemiologically, the disease has been studied in many different clinical settings, but little is known about it in cancer patients, a population at increased risk for thrombosis and thus exposure to heparin products. Additionally, thrombocytopenia is a common finding in cancer patients. The convergence of these variables highlights the importance of an increased understanding of the disease in cancer patients.