Clinical signs, radiological, arthroscopic findings and magnetic resonance imaging features of a male German shepherd dog with incomplete ossification of the humeral condyle are described. The dog showed recurrent left forelimb lameness and pain on elbow palpation. In routine radiographs, the lesion was obscured. In oblique radiographs, a radiolucent line was detected, and magnetic resonance imaging clearly demonstrated a defect in the humeral condyle. However, arthroscopy showed no changes or discontinuity of the humeral cartilage. Incomplete ossification of the humeral condyle may be underrepresented in conventional, routine studies because if there is concurrent additional elbow pathology (for example fragmented coronoid process), treatment may lead to clinical improvement and further diagnostic techniques may not be performed. The benefit of magnetic resonance imaging in this case is demonstrated.