Osteochondritis dissecans can affect any joint, although the ankle is the third most common location after the knee and elbow. When the ankle is involved, the lesion usually affects the talar dome. The authors report a case of osteochondritis of the subtalar joint affecting the talus in a 14-year-old girl without any history of trauma. Plain radiographs did not show any bony pathology, and the diagnosis was made with computerized tomography. The patient was treated initially in a non-weight bearing plaster cast with antiinflammatory medication and subsequent physiotherapy. The conservative treatment failed to relieve her symptoms, and she underwent subtalar arthroscopy followed by surgical excision, curettage, and drilling through a mini-arthrotomy. Postoperatively, the patient was managed with protected weight bearing and physiotherapy. A year after surgery, she had returned to her routine activities, including sports, with no further complaints related to the affected foot.