The purpose of this study was to assess the long-term results of an extended soft tissue release in a single procedure, for the treatment of congenital idiopathic clubfoot. Seventeen patients with 22 congenital idiopathic clubfeet were treated surgically with the 12-in-1 procedure. The majority of cases were grade III (severe) deformities. The procedure consisted of dividing or lengthening 12 elements of the posterior, medial, and plantar side of the foot. The mean follow-up period was 11 years (range, 7-18 years). Revision surgery was required within 1 to 3.5 years of the initial procedure in four cases (residual deformity), whereas in another patient, bilateral camptodactyly was corrected 11 years postoperatively. At the time of the most recent follow-up, and after the revision procedures in patients with residual or recurrent deformities, results were excellent in 8 and good in 14 cases. The long-term follow-up results of the 12-in-1 procedure are encouraging for the treatment of idiopathic congenital clubfoot.