Abstract: Small cell lung cancer (SCLC), which accounts for about 15% of lung cancer cases, is an aggressive disease characterized by rapid growth and early widespread metastasis. Despite sensitive to chemotherapy and radiotherapy, SCLC is vulnerable to get resistant and has high recurrence rates. Therefore, novel therapies are desperately needed to improve treatment efficacy and increase overall survival. A complex molecular biological alteration of SCLC accounts for its pathogenesis and chemo-resistance. With the understand -ing of SCLC biologic behavior and improvement of detection technique, immunotherapy may be a viable therapeutic approach and bring breakthrough to the treatment of patients with SCLC. In this review, we will discuss the rationale for immunotherapy and recent clinical trials of immunotherapeutic agents for SCLC.