The author presents two examples of metastatic endometriosis occurring in an abdominal scar. These case reports illustrate the two main theories of the pathogenesis of the condition: transportation and metaplasia. The diagnosis is straightforward in the classic case in which a painful mass fluctuates with the menstrual cycle, but a biopsy may be needed to confirm the diagnosis when the history is atypical. The treatment of choice, for those who require treatment, may be hormonal manipulation, surgery or irradiation, or a combination of these.