One hundred fifty-seven consecutive patients with small cell lung cancer seen at the National Cancer Institute over a four-year period underwent a series of pretherapy liver staging procedures to determine optimal means of detection and prognostic implications of hepatic metastases. Liver evaluation included physical examination, liver function tests, and liver scan (radionuclide or computerized tomography [CT]), as well as percutaneous and/or peritoneoscopy-directed liver biopsy when possible (74%). Liver metastases were detected in 26% of patients. Peritoneoscopy was the most sensitive method of liver evaluation and increased the detection of liver metastases when done in a sequential fashion after percutaneous liver biopsy from 18 to a total of 27 patients. Of the noninvasive procedures, radionuclide and CT liver scan were the most accurate concurring with liver biopsy in 87% of patients but permitting correct discrimination of stage in excess of 96% of patients. The accuracy of this noninvasive procedure was enhanced by an algorithm combining the results of radionuclide liver scan with liver function tests to detect patients with high or low likelihood of liver involvement. The survival and response of patients with liver metastases was significantly worse than those without such metastases with no three-year disease-free survivors among patients with liver metastases.