Abstract The prognosis of osteochondritis dissecans (OCD) depends on the age of manifestation and the size of the lesion. Before epiphyseal closure, OCD usually responds well to the restriction of the patient's sporting activities. Surgical intervention is not always necessary. However, if the disease manifests after epiphyseal closure, it often needs surgical treatment because the lesion is usually found at an advanced stage (International Cartilage Repair Society [ICR] OCD II or more). Furthermore, if a massive lesion develops to separation (ICR OCD II or III) or displaced loose bodies (ICR OCD IV), despite restriction of sporting activities, the prognosis is poor. This report discusses 2 cases of OCD. One patient had a massive stage ICR I lesion, although the disease was found before epiphyseal closure. In the other patient, a 22-year-old man, a large separated fragment (ICR OCD IV) was found after epiphyseal closure. The separated surfaces of the fragment and the mother bed had become sclerotic. Cylindrical osteochondral grafts using jigs for Mosaicplasty (Smith & Nephew, Andover, MA) were performed on the 2 patients, both of whom made successful recoveries. These cases suggest that cylindrical osteochondral grafting is a useful procedure for difficult cases of large lesion size or late manifestation.