The influence of various sites of distant metastases on response and survival was analyzed in 106 consecutive previously untreated patients with small cell carcinoma whose disease was systematically staged. All patients received 6 wk of intensive induction chemotherapy with cyclophosphamide, methotrexate, and lomustine; therapy thereafter varied without differential effects on survival. Staging procedures included physical examination, chest roentgenogram, fiberoptic bronchoscopy, bone marrow and liver biopsies, and radionuclide bone, brain, and liver scans. On the basis of pretreatment staging, 33 patients (31%) had limited disease. In the remaining 73 patients, sites of extensive disease included bone in 40; with bone as the sole site of metastatic disease in 13; liver in 30, with liver as the only site in 5; soft tissues in 25 (only site in 7); bone marrow in 22 (only 2); central nervous system in 9 (only site in 4); opposite lung in 7 (only site in 4). Although patients with limited disease live longer than those with extensive disease (median length of survival, 12 versus 10 months), this difference was not significant. This lack of major impact of traditional stage on survival was explained by the similar survival of patients with limited disease and a single site of extensive disease. Prognosis worsened with increasing number of sites of extensive disease (median survival, 11.5, 10, and 8 months for one, two, and three or more sites, respectively). Metastases to the liver or central nervous system significantly shortened survival, whereas involvement of bone, soft tissues, or bone marrow had little adverse effect. In patients with small cell carcinoma whose disease is thoroughly staged and who are given aggressive chemotherapy, certain sites or a small number of sites of extensive disease may be treated as successfully as limited disease.