We investigated whether intensive follow-up leads to earlier diagnosis of recurrence, more effective treatment, and longer survival in patients with small cell lung cancer (SCLC) who had shown a complete or partial response to first-line chemotherapy. The subjects of this retrospective study were 94 patients with SCLC who had shown a complete or partial response to first-line chemotherapy. The patients were separated into two arms: an intensive follow-up arm in which patients underwent regular blood tests, chest radiography, computed tomography of the chest and upper abdomen, magnetic resonance or computed tomography of the brain, and bone scintigraphy bimonthly for 6 months and then quarterly for 1.5 years; and a nonintensive follow-up arm in which these examinations were performed at the physician's discretion. All patients also underwent interviews and physical examinations monthly for 2 years and bimonthly for a further 3 years. Patient characteristics did not differ significantly between the arms. Disease recurred in 55 of 62 patients of the intensive arm and 29 of 32 patients of the nonintensive arm. Asymptomatic recurrences were detected more frequently in the intensive arm than in the nonintensive arm. The response rate to salvage therapy among all patients with recurrent disease was significantly higher in the intensive arm (61.8%) than in the nonintensive arm (37.9%; p=0.04). Both median postrelapse survival and overall median survival were significantly longer in the intensive arm (9 and 20 months, respectively, p=0.04 and p=0.001) than in the nonintensive arm (4 and 13 months, respectively). Intensive follow-up helps detect recurrence earlier, enhances the effectiveness of treatment, and lengthens survival in patients with SCLC. Well-designed prospective, randomized trials including a cost-benefit analysis are needed to compare intensive and nonintensive follow-up regimens.