Continuous passive motion has been shown to be effective in the conservative treatment of idiopathic club foot. We wished to determine whether its use after operation could improve the results in resistant club feet which required an extensive soft-tissue release. There were 50 feet in the study. Posteromedial lateral release was performed in 39 feet but two were excluded due to early relapse. The mean age at surgery was eight months (5 to 12). Each foot was assigned a Dimeglio club foot score, which was used as a primary outcome measure, before operation and at 6, 12, 18 and 44 months after. Nineteen feet were randomly selected to receive continuous passive motion and 18 had standard immobilisation in a cast. After surgery and subsequent immobilisation in a cast the Dimeglio club foot score improved from 10.3 before to 4.17 by 12 months and to 3.89 at 48 months. After operation followed by continuous passive motion the score improved from 9.68 before to 3.11 after 12 months, but deteriorated to 4.47 at 48 months. Analysis of variance adjusted for baseline values indicated a significantly better score in those having continuous passive motion up to one year after surgery, but after 18 and 48 months the outcomes were the same in both groups.