Osteochondritis dissecans is a lesion of subchondral bone with subsequent involvement of the overlying cartilage. Although the etiology of the disease is unknown, mechanical, traumatic, and ischemic etiologies have been suggested, in addition to developmental and genetic factors. There are several treatment options depending on the stage of the disease and surgeon preference. The use of a fresh osteochondral allograft for treatment of a lesion of the femoral condyle is relatively new, and we report its use in a unique situation involving identical twins who both presented with osteochondritis dissecans of the same anatomic location within 2 years of each other. Since these were identical lesions in identical twins, this commonality supports the suggestion that some genetic component may be present in the etiology, especially in this situation where a genetic connection existed. We recommend genetic studies to determine the extent of genetic influence on the disease.