Abstract: Objective We prospectively evaluated the efficacy and toxicity of 3-dimensional conformal radiotherapy(3D-CRT)for patients with unresectable hepatocellular carcinoma(HCC)after first incomplete transcatheter arterial chemoembolization(TACE).Methods Between January 2008 and January 2010,50 patients with unresectable HCC with incomplete uptake of iodized oil were randomly divided into two groups.TACE group(25 patients)was performed 2~3 cycles by using Lipiodol and adriamycin embolization according to disease.TACE +3D-CRT group(25 patients)was added three-dimensional conformal radiotherapy.Tumor response was evaluated by changes in tumor size on serial computed tomography scans,and toxicity was evaluated by the Common Terminology Criteria for Adverse Events v3.0.Results The average diameter of tumor before and after treatment were(8.37± 9.15)cm and(4.22 ± 5.66)cm in TACE group,respectively.The tumor diameter before and after treatment were(8.65± 6.89)cm and(3.86 ± 4.32)cm in TACE +3D-CRT group,respectively.There was significant decrease in tumor size in both TACE group(P＜0.05)and TACE +3D-CRT group B(P＜0.05).There was no significant differences between the two groups in tumor response(P＞0.05).An Objective response was achieved in 13 of 25 lesions(52.0%),with a complete response in 4 lesions(16.0%)and partial response in 9 lesions(36.0%).The overall survival rate was 64.0% at 1 year.There was no grade III or greater acute toxicity.Conclusion This study shows that the application of 3D-CRT could be more considered for patients with incomplete uptake of iodized oil than single TACE.