Four types of instability or disruption of the proximal tibiofibular joint were found in a compilation of forty-three cases. These were classified as subluxation, anterolateral dislocation, posteromedial dislocation, and superior dislocation. Idiopathic subluxation of the proximal end of the fibula appeared to be a self-limited condition of youth, with decreasing symptoms as the patient approached skeletal maturity. Anterolateral dislocation was the most common injury encountered. Unfortunately, the diagnosis was initially missed in about one-third of the cases. Most cases responded satisfactorily to closed reduction. Several of the dislocations developed into either a chronic subluxation or arthritis of the proximal tibiofibular joint. Two surgical approaches were used to alleviate these complications, arthrodesis of the joint and resection of the proximal end of the fibula. Arthrodesis of the proximal tibiofibular joint was complicated by a prolonged period for fusion, as well as by eventual development of pain and instability in the ankle. In contrast, resection of the proximal end of the fibula was associated with significantly more satisfactory results in long-term follow-up. Posteromedial dislocations proved more unstable after initial reduction.