Epidemiological studies of Peyronie's disease (PD) reported the prevalence of this condition as much higher than once thought, highlighting the potential physical and psychosocial impact of the disease on society. For this reason, knowledge of the epidemiology of PD is important for allocating and managing health care resources and assessing intervention strategies. The true prevalence of PD is unknown; it is estimated as between 3.7% and 7.1%, but the actual prevalence of this disease may be higher because of patients' reluctance to report this embarrassing condition to their physicians for cultural and psychological reasons. Several risk factors, such as hypertension, diabetes, hyperlipidemia, and smoking, have been suggested. The estimated prevalence of PD at younger ages is around 8% and shows a more acute onset and a lower incidence of associated erectile dysfunction. This chapter reviews the contemporary state of knowledge of the epidemiology of PD.