Certain prognostic factors for small cell lung cancer (SCLC) have been validated, but the prognostic role of 18F-FDG PET/CT still remains unclear. The aim of this study was to evaluate the prognostic significance of 18F-FDG PET/CT in patients with SCLC. We reviewed 142 patients with pathologically proven SCLC who underwent pre-treatment 18F-FDG PET/CT. Standardised uptake value (SUVmax) and other potential prognostic variables were chosen for analysis. The mean age of the study population was 58.2 ± 10.1 years (range, 25-84), and 124 (87.3%) patients were men. The median SUVmax value was 11.6 (4.0-29.3). Among the variables included in the univariate analysis, performance status (P = 0.001), disease stage (P < 0.001), administration of thoracic radiotherapy (TRT; P < 0.001), albumin level (P = 0.030) and LDH level (P < 0.001) showed prognostic significance. Further, multivariate analysis showed that performance status (P = 0.007), albumin level (P = 0.002), LDH level (P < 0.001) and administration of TRT (P = 0.001) were independent prognostic factors for survival. In conclusion, performance status, TRT, LDH level and albumin level were identified as important prognostic factors, while 18F-FDG PET/CT uptake of the primary lesions did not have any prognostic significance for survival in patients with SCLC.