The proper management of the rigid flat-foot requires an accurate diagnosis since the condition is treated on causal or rational basis. Calcaneonavicular coalition best seen on an oblique view of the foot may be treated by resection of the coalition with extensor digitorum brevis interposition. If the diagnosis is made sufficiently early, the resection can lead to an essentially normal foot. Coalition between the talus and the calcaneus may occur in the posterior, middle or anterior facet. The most common coalitions are seen in the middle facet area followed by those in the anterior facet with the posterior facet coalition rarely being seen. Coalitions in the area of the middle facet are usually managed nonoperatively; triple arthrodesis is used only if symptoms are not relieved by nonoperative measures. Resection of a talocalcaneal coalition in the middle facet is rarely indicated but occasionally will give relief when the coalition either presses on the medial plantar nerve or causes a mechanical disturbance of the ankle. Anterior facet coalitions should receive a trial of cast immobilization but frequently require triple arthrodesis. Other conditions such as rheumatoid and post-traumatic arthritis will frequently respond to a period of immobilization in a plaster cast. Triple arthrodesis has not been required in rheumatoid arthritis in the author's series but occasionally is necessary in the post-traumatic rigid flatfoot. Other rare causes of the rigid flatfoot should be kept in mind for a complete diagnostic evaluation since even a neoplasm (fibrosarcoma) has been reported to cause this symptom complex.