The authors present a clinical of umbilical endometriosis in a young woman. This patient never underwent any operation or diagnostic abdominal procedures. The case is very interesting because of problems concerning differential diagnosis with other umbilical and periumbilical diseases and pathogenetic theories. In this study the authors suggest a hypothesis to explain the localizazion of ectopic endometrium in this site. We review the literature, with some comments on therapeutic options; finally we compare the medical and the surgical approach and we suggest an advisable therapy.