The records of 87 patients with small cell lung cancer were reviewed. Patients were clinically staged with bone marrow aspirate and biopsy as well as radionuclide scans of bone, liver, and brain. Extrathoracic spread was noted in 54% (47/87) and limited disease in 46% (40/87). The bone marrow evaluation was positive in 13/62 patients (21%) and seven of these thirteen patients had normal bone scans (54%). Of these seven patients, five had no other evidence of distant metastases and their survival was 7-10 months, considerably shorter than patients found to have limited disease. Bone marrow examination appears to complement radionuclide scanning in the initial staging of patients with small cell carcinoma of the lung and provides important prognostic information.