Objective: To evaluate the clinical efficacy and toxicity of simultaneous integrated boost intensity-modulated radiotherapy(SIB-IMRT) in patients with stage Ⅲ small cell lung cancer(SCLC).Methods: From January 2010 to August 2012, 40 patients with stage Ⅲ SCLC who received definitive SIB-IMRT in our hospital were retrospectively examined.The median age was 59 years old, and patient ages ranged from 41 to 71 years old.Nineteen(47.5％) patients had stage ⅢA and 21 (52.5％) patients had stage ⅢB SCLC.The prescribed dose was 60 Gy in 30 fractions at 2.0 Gy per fraction to the pGTV, and 54 Gy in 30 fractions at 1.8 Gy per fraction to the planning target volume (PTV).