Abstract: Objective To investigate the safety and efficacy of ultrasound( US)- guided percutaneous radiofrequency ablation( RFA) for primary hepatic carcinoma adjacent to the diaphragm. Methods This study included 277 patients with 362 lesions of primary hepatic carcinoma managed with US- guided percutaneous RFA in 302 Hospital of PLA from January 2011 to October 2014. Sixty- six patients with 71 hepatocellular carcinomas( HCCs) located less than 5 mm from the diaphragm were in study group,and 95 patients with 114 HCCs located more than 10 mm from the hepatic surface were in control group. The patients' symptoms and complications were observed after the therapy.The complete ablation rate,local tumor progression rate,and complication rate were compared between the two groups. Comparison of continuous data between the two groups was made by independent- samples t test,while comparison of categorical data was made by chi-square test. Results At one month after operation,65( 91. 5%) of 71 tumors in the study group and 107( 93. 9%) of 114 tumors in the control group achieved complete ablation,according to contrast- enhanced CT and MRI,and there was no significant difference between the two groups( χ2= 0. 36,P = 0. 55). The postoperative follow- up showed that the local tumor progression rates in the study group and control group were 16. 9% and 13. 2%,respectively,without significant difference between the two groups( χ2= 0. 49,P = 0. 48). In the study group,22 patients developed adverse reactions,versus 37 patients in the control group( χ2= 2. 60,P = 0. 11). Conclusion US- guided percutaneous RFA is a safe and effective means for the treatment of primary hepatic carcinoma adjacent to the diaphragm.