PURPOSE: To determine the characteristic MR imaging findings of Brodie's abscess in pediatric patients. MATERIALS AND METHODS: We retrospectively reviewed 17 pediatric patients with surgically-proven or clinically and radiologically diagnosed Brodie's abscess who had undergone T1- and T2-weighted spin-echo sequences, T2-weighted fast spin-echo sequence and gadolinum enhanced MR imaging. The MR imaging findings were analysed and classified according to the signal characteristics of the abscess and srrounding bone marrow. RESULTS: The MR imaging findings of Brodie's abscess could be classified as one of three types, as follows : Type I (10/17) was seen as a target appearance with four layers ; i.e. a center with low signal intensity on T1-weighted images and high signal intensity on T2-weighted images; an inner rim of high signal intensity, as compared with muscle on both T1- and T2-weighted images with intense contrast enhancement; an outer rim of low signal intensity on both T1- and T2-weighted images, and a peripheral halo of low signal intensity on T1-weighted images and variable signal intensity on T2-weighted images. In type II (4/17), there was no distinction between the center and the inner rim on T1-weighted images, but a clear distinction on contrast enhanced images by intense enhancement of the inner rim. In type III (3/17), there was no distinction between the center and the inner rim on either T1-weighted or contrast enhanced images, due to diffuse enhancement of the lesions. Additional findings of Brodie's abscess include epiphyseal plate violation (8/17), linear or tubular sinus tracts (7/17), inflammatory reaction or edema of surrounding soft tissue (7/17), periosteal reaction (1/17), and pyogenic arthritis (1/17). CONCLUSION: MR imaging is a useful diagnostic tool for the characterization and determination of the extent of Brodie's abscess. Contrast enhanced MR imaging is particularly valuable for the evaluation of type II lesions.