Traumatic elbow dislocations account for approximately 3% to 6% of childhood upper extremity injuries, and 41% of these dislocations are concomitant injuries around the elbow. Most of these injuries are associated with a fall on an outstretched hand. Compartment syndrome is one recognized complication after elbow dislocation and distal humeral and radial neck fracture. Compartment syndrome in the forearm is a devastating complication in children with forearm, elbow, and supracondylar fractures. Compartment syndrome occurs as the result of hypoxic damage caused by interruption of the circulation to the muscles. Any evidence of compartment syndrome requires compartment pressure measurements and possibly fasciotomy. Fasciotomy is recommended in the presence of clinical signs of compartment syndrome, such as undue pain (out of proportion to severity of injury), pallor, paresthesia, absent or deficient pulse, and paralysis of the limb. Osteochondral flap avulsion fracture is a rare clinical presentation in pediatric elbow injuries. To our knowledge only 8 cases have been reported in the literature. Our case is different from others in terms of delayed presentation, and is associated with olecranon fracture and forearm compartment syndrome. This case reemphasizes the anatomy of the semilunar notch of the proximal ulna and the importance of careful clinical and radiological examination in the treatment of childhood elbow injuries.