Osteochondritis dissecans (OCD) is an idiopathic condition affecting the articular epiphysis. Initially described in the knee, this entity affects several other parts of the body such as the talar dome, tarsal navicular, and femoral capital epiphysis. Osteochondritis dissecans (OCD) of the elbow is typically located in the capitellum of the humerus in young teenagers. OCD of humeral trochlea is very rare, but can be occurred among young athletes. OCD developed medial trochlea was extremely rare, especially, without any other trauma. We present a patient, pitcher with OCD in the medial trochlea of the humerus who underwent arthroscopic debridement and microfracture.