Deviation of the penis may be congenital or acquired. The latter, also known as Peyronie's disease, is seen in 0.4-9% of patients. The aetiology is not fully understood, but the hypothesis is that microtrauma leads to scar tissue formation, plaques, which deform the penis. The disease is divided into a first, painful, progressive, inflammatory phase and a latter, steady, chronic phase. The symptoms are mainly sexual dysfunction and psychological problems. Surgery is recommended in congenital cases and in the chronic phase of Peyronie's disease, where the medical treatment has not been convincing.