Acquired adult flatfoot deformity is a commonly encountered entity in orthopaedic practice. It results mainly from posterior tibial tendon (PTT) dysfunction, is more common in women and frequently associated with obesity. The four severity stages are based on dysfunction of the PTT, on the reducibility of the deformity, and on the condition of the hindfoot joints. Conservative treatment is functionally efficient in the early stages and may also contribute to analgesia in advanced stages. The goal of surgery is to restore a functional mobility in the early stages and to achieve rigid stabilization of the hindfoot in the late stages. The treatment's choice and the control of the predisposing factors for acquired flatfoot depends upon a close collaboration between the family physician and the orthopaedic surgeon.