In a series of 643 patients with small cell lung cancer (SCLC), 55 patients (8.6%) had signs or symptoms of superior vena caval obstruction syndrome (SVCO). Relatively long intervals from the onset of the first symptoms of SVCO to the start of therapy were observed, and invasive diagnostic procedures were safely performed in most patients. The pretreatment characteristics of patients with SVCO were not significantly different from those of patients without signs of the syndrome, and survival was similar in both groups. Patients with SVCO were usually treated first with induction chemotherapy, and prompt resolution of signs and symptoms occurred in the majority. Radiation was effective in controlling SVCO at relapse or after failure of initial chemotherapy. It was concluded that SVCO in patients with SCLC should be treated initially with systemic chemotherapy, as for other presentations of this disease. The current data do not support the commonly held view that SVCO in SCLC should be approached as an oncologic emergency.