Objective To analyze the clinical features, prognostic factors, and role of radiotherapy in combined small cell lung cancer (C-SCLC). Methods A retrospective analysis was performed in 44 patients who were histologically diagnosed with C-SCLC from January 2005 to December 2011. The Kaplan-Meier method was used to estimate survival, and the log-rank test was used for univariate prognostic analysis. Results The follow-up was 100%. Fourteen patients were followed up for at least 3 years, and 9 patients for at least 5 years. The 1-, 3-, and 5-year overall survival (OS) rates were 69%, 47%, and 33%, respectively, and the 1-, 3-, and 5-year progression-free survival rates were 53%, 44%, and 32%, respectively. The univariate analysis showed that Karnofsky performance scale (KPS) score of<80(P=0.006), presence of non-squamous cell carcinoma (P=0.006), tumor diameter of>3 cm (P=0.049), and positive surgical margin (P=0.001) were associated with poorer OS. Radiotherapy significantly improved the OS in patients with stage Ⅲ_A/Ⅲ_B disease (P=0.032), positive lymph nodes (P=0.006), or over 4 positive lymph nodes after surgery (P=0.025), and it nonsignificantly improved the OS in patients with T₃—T₄ disease (P=0.179). Conclusions C-SCLC is mostly in limited stage, and multimodality therapy is recommended. KPS score of<80, presence of non-squamous cell carcinoma, tumor diameter of>3 cm, and positive surgical margin are poor prognostic factors. Radiotherapy can improve the OS in patients with stage Ⅲ_A/Ⅲ_B disease, positive lymph nodes, or over 4 positive lymph nodes after surgery.