Small cell lung cancer (SCLC) accounts for 20% to 25% of cases of bronchogenic carcinoma and results in pronounced morbidity and mortality in the United States. More than 90% of cases of SCLC are caused by cigarette smoking. Common pulmonary manifestations are dyspnea, persistent cough, hemoptysis, and postobstructive pneumonia. At the time of diagnosis, patients usually have extensive disease. To date, therapeutic approaches have made only modest advances in outcome. Combined modality approaches, such as radiotherapy administered concomitantly with the initiation of chemotherapy, induction chemotherapy followed by radiotherapy administered during the subsequent courses of chemotherapy, sequential chemotherapy and radiotherapy, and courses of radiotherapy split between cycles of chemotherapy, are important for improving survival in patients with SCLC.