Complex idiopathic clubfeet are distinguished by significant shortening, rigid equinus with a deep crease above the heel, severe plantar flexion of all metatarsals, a deep plantar crease seven across the full width of the sole of the foot and high cavus with a short and hyperextended big toe. Ponseti has devised a modified technique for treating complex clubfeet. We retrospectively identified 11 children (nine males and two females) with 17 complex clubfeet who were treated with the modified Ponseti method. Demographics, severity of clubfoot, number of casts, rate of tendoachilles tenotomy, relapse rate and their management, any additional procedures and data on complications were collected. The average follow-up was 7 years (range 3–11 years) and the average Pirani score was 5.5 (range 4.5–6.0). Initial correction was achieved in all children, with an average of 7 (range 5–10) Ponseti casts. Tendoachilles tenotomy was performed in all 17 feet (100%). The overall relapse rate was 53% (nine feet). Five relapses were managed successfully with repeat casting and four feet were subjected to a second tendoachilles tenotomy. Four feet required extensive surgical releases. A satisfactory outcome was achieved at the final follow-up in 13 of 17 feet (76.5%). Two of these children (two feet) required an additional tibialis anterior transfer. In our experience, the modified Ponseti method is an effective first-line treatment for complex idiopathic clubfoot; however, such children will often require more casts than usual and have a higher rate of tendoachilles tenotomy and a higher risk of relapse requiring surgical procedures. Level of Evidence: level IV.