Purpose : The purpose of this study is to assess the sonographic findings of Osgood-Schlatter disease withcorrelation to radiographic findings and to determine value of sonography in the diagnosis of Osgood-Schlatterdisease. Materials and Methods : The population consists of 22 cases of Osgood-Schlatter disease and 15 healthysubjects of the same age range for comparison. The sonographic study was carried out with real time units equippedwith linear probe of 7 MHz frequency. Radiography and sonography were done in all cases and follow-up sonographywas performed in 10 cases. Results : The sonographic features of the Osgood-Schlatter disease were swelling ofcartilage over the anterior tibial tuberosity ossification center in 16 cases, fragmentation and/or irregularitiesof the ossification center of the anterior tibial tuberosity in 14 cases, localized thickening of the patellartendon in 14 cases, ossicles in the thickened patellar tendon in 3 cases, and distension of the infrapatellarbursa in 2 cases. Fifteen of 22 cases of Osgood-Schlatter disease had abnormal findings on radiographs andsonograms. Out of 7 cases which had normal radiograph and abnormal findings on sonogram, 6 cases showed patellartendon thickening, cartilage swelling, and/or distended infrapatellar bursa and one case showed fragmentation ofanterior tibial tuberosity on sonogram. Conclusion : Sonographic evaluation of Osgood-Schlatter disease provided aclear picture about pathologic changes in the superficial soft tissues and in the cartilage and also yielded thesame diagnostic information on bony change as radiography Sonography is a reliable and useful method for theevaluation of young patients with clinically suspected Osgood-Schlatter disease.