The clinical and radiological findings in 7 cases of osteochondritis dissecans of the talus indicate that this is a potentially progressive condition. Surgical treatment was carried out in 4 cases while the remaining 3 were treated conservatively. Surgery produced good clinical and radiological results. The conservative treatment consisted of immobilisation and abstention from weight-bearing. This was unsuccessful in 2 adult patients but in a 9 year old girl it led to a virtually complete recovery in 3 months.