Upper abdominal CT scans were performed on 45 consecutive patients with biopsy proven but previously untreated small cell carcinoma of the lung. Evidence of metastases was found in 16 (36%) patients. The most common site of metastases was the liver (27%). CT had a sensitivity of 88% and specificity of 94% as compared with biopsy results. Evidence of retroperitoneal metastases was found in seven (16%) patients.