Although patients with lung cancer have benefited from advances in diagnostic techniques, surgery, chemotherapy, and radiation, infection frequently complicates the course of cancer treatment. Infection may be caused by the tumor itself, by antineoplastic therapy, or by supportive care measures. Recognition of risk factors for infection is critical. The relationship between an underlying immune defect and certain infections is well documented. Diagnosis may be complicated by the paucity of signs and symptoms or by an atypical presentation. Prompt institution of empiric antimicrobial therapy is usually warranted, particularly in life-threatening infections. This review will focus on the epidemiology, diagnosis, and management of particular infections that can occur in patients with lung cancer.