PURPOSE: We retrospectively classified the young adult Osgood-Schlatter disease by plain radiography and accessed the relationship between bone scan results and symptom duration. MATERIALS AND METHODS: From 2004 to 2007, young adults with symptoms of Osgood-Schlatter disease were included in the study. The patients were classified into 3 groups, protrusion, cleft and ossicle, according to their radiographic results. All patients had bone scan exams, we analyzed the correlation between the bone scan results and the duration of symptoms. RESULTS: All patients were male with average age of 19.8 (18.5~22.0) years old. Out of 59 patients, 27 were bilateral. Of 86 knee joints, 36 came out positive with bone scan. Positive bone scan rate was 11.1% in protrusion type, 40.0% in cleft type and 61.4% in ossicle type. The pain persisted longer in ossicle type than the others. The symptom duration correlated with the bone scan results. CONCLUSION: We classified young adult Osgood Schlatter disease as three types. The ossicle type of Osgood-Schlatter disease has longer symptom duration, which correlates with the bone scan results. The bone scan result can be one of reliable reference factors for the treatment of young adult Osgood-Schlatter disease.