In our study, we aimed to demonstrate whether a complex iatrogenic clubfoot really exists; identify the causative mechanisms; and determine the outcome if properly treated. We observed 54 clubfeet previously treated unsuccessfully by manipulation and casting elsewhere. All the feet had been classified at diagnosis as typical clubfeet. In 26 cases, the cast had slipped down, entrapping the foot in a plantar-flexed position. Nine clubfeet out of those 26 cases presented the clinical features of a complex iatrogenic deformity. These were treated with the modified Ponseti protocol and evaluated at follow-up according to the International Clubfoot Study Group Score. The length of follow-up averaged 7.2 years. Two feet showed an excellent result, five feet showed a good result, and two feet showed a fair result. The relapse rate was 55% in complex clubfeet. Relapsed clubfeet were treated by Achilles tenotomy or lengthening and anterior tibial tendon transfer. We believe that faulty manipulation and a poor casting technique may convert a typical clubfoot into a complex iatrogenic deformity. Risk factors include severe clubfoot, short and stubby foot, and unmolded casts slipping down.