Introduction: The aim of this study is to evaluate the effectiveness of the Ponseti method in children presenting before 1 year of age with either untreated or complex (initially treated unsuccessfully by other conservative methods) idiopathic clubfeet. Patients and methods: The authors report 134 feet of 92 patients with Dimeglio grade 2, 3, or 4 deformities treated with the Ponseti method. Twenty-four percent of feet were of complex deformities at initial presentation to the authors’ clinics. Results: At a mean follow-up of 46 months (range 24–89) we avoided joint release surgery in 97% of feet. Sixty-seven percent required a percutaneous tenotomy of the Achilles tendon. Relapse rate was 31% (41 feet). We treated 2 relapses by restarting the use of orthosis, 17 with re-casting, 18 with anterior tibial tendon transfer following a second relapse, and 4 feet with extensive joint surgery. Compliance with the use of orthosis was identified as the most important risk factor (P<0.0001) for relapses. Previous unsuccessful treatment attempts by other conservative methods did not adversely affect the results unless the cases had iatrogenic deformities. Cases with iatrogenic deformities from previous treatment had a significantly increased risk of non-compliance and relapse. Experience of the treating surgeon and cast complications were also related to relapses. Conclusion: Our results show that the Ponseti technique is reproducible and effective in children at least up to 12 months of age. It can also produce good correction in children presenting with complex idiopathic deformities. Therefore, extensive joint releases should not be considered immediately in such cases. The treating surgeon should be meticulous in using the technique and ensure compliance to foot abduction brace in order to avoid recurrences.