Osteochondritis dissecans (OD) involves the adolescent radio-capitellar joint and is due to chronic, compressive forces on the capitellum, ultimately causing injuries ranging from an articular cartilage injury to an osteochondral avulsion fracture. Plain films are often negative, while CT, MRI and MR arthrography are the examinations of choice. OD should not be confused with a pseudodefect of the capitellum or Panner's disease. Staging of the lesion is important for its management, which is conservative for stages 1 and 2, while surgery is indicated for stages 3 and 4. Osteoarthritis is a late complication in 50% of patients with advanced disease.