Nineteen patients showing radiological subchondral changes in the trochlea tali are submitted. In 16 cases the changes were osteochondritis dissecans, either with sequestra or with multilocular cysts, and in three cases so-called synovial cysts. The site was in 13 cases the upper medial and in five cases the upper lateral angle of the talus, and in one patient both. In five of the six lateral cases symptoms had started following trauma, while this applied to only five of the 13 medial cases. The three solitary cysts showed marked similarity to the other cases with respect to symptoms, signs, operative findings, as well as possible traumatic aetiology.