Aim of work: The aim of this study is to assess technical success and the complication rate of sonographically guided percutaneous liver biopsies in infants and children compared to the transthoracic percussion guided technique. Methods: we conducted a randomized case control study for all cases who were scheduled for performing liver biopsy in the Pediatric Hepatology Unit in Cairo University Pediatric Hospital from the begining of January 2013 to the end of June 2013. All patients were randomly divided into 2 groups; a group who underwent a transthoracic percussion guided technique while the second one underwent an ultrasound guided biopsy. Patients were subjected to full history taking, complete examination and pre-procedure investigations and they were monitored pre-, during and post- biopsy and were compared to each other regarding the success in obtaining an adequate liver tissue specimen for histopathological diagnosis and the complication rate.Results: The median age of the patients was 2.5 months with IQR of 13, the most common indication was cholestasis by 72.5 %. The overall rate of complications was 13.7%. Major complications (involving intraperitoneal collection, need for blood transfusion and mortalities) were encountered in 5/102 (4.9%) patients; 4/57 (7%) patients of the percussion guided group versus 1/45 (2.2) in the ultrasound guided group, while the remaining 9/102 (8.8%) patients; 6/57 (10.5%) patients of the percussion guided group versus 3/45 (6.7%) of the ultra sound guided group were considered to have minor complications. Specimens were considered adequate in 99 out of 102 cases (97%) whereas in only 3 cases done with the percussion guided technique, the withdrawal of an adequate tissue specimen failed (3%) and one patient did the biopsy in a later visit. Mean length of the specimens in mm was 14 ± 8 in the percussion guided group versus 15 ± 7 in the ultrasound guided group. No differences were observed between both groups neither in the retrieved specimen length nor in the complication rate. Conclusion: There are no significant differences between percussion guided biopsy and the ultrasound guided biopsy in terms of adequacy of biopsy samples or complication rates. Ultrasound guidance could be reserved to obese uncooperative children, a suspected focal lesion or with decreased operator experience.