Osteochondritis dissecans most often affects the convex articular surfaces of the knee, the elbow, and the ankle joints; other sites of manifestation are very rare. Here we report a case of osteochondritis dissecans of the talonavicular joint affecting the concave part of the tarsal navicular bone in a 22-year-old woman, which was successfully treated by surgery, leading to complete recovery. Early diagnosis and surgery in stages of undamaged cartilage may help to prevent disease progression and the development of disabling osteoarthritis in the physiologically heavily loaded talo-navicular joint.