Rupture of the posterior tibial tendon results in a progressive, painful flat-foot deformity. Other physical findings are an inability to invert the heel on tip-toe standing and loss of inversion power. In this study we report on seventeen patients with this condition who were surgically treated with a transfer of the flexor digitorum longus tendon into the navicular or an advancement of the posterior tibial tendon. Follow-up results were excellent in twelve, good in one, fair in three, and poor in one patient. Arthrodesis of the talonavicular and calcaneocuboid joints was subsequently done for the patient with the poor result.