Rare occurrence, absence of specific clinical manifestations, difficult diagnostics on early stages, and insufficient experience in treatment of endometriosis genitalis externa deserve special attention. The study summarizes the results of treatment of scar endometriosis in four patients (three of reproductive and one of late reproductive age) describing clinical and diagnostic peculiarities of all cases. We revealed no specific laboratory diagnostic criteria of the pathology. The article is illustrated with photos of ultrasound findings, surgical field, a fragment of scar tissue removed during the surgery, and photomicrographies of surgical specimen histological sections. All presented pictures are described with indication of pathological process markers. We have stated the discrepancy between the sizes of endometrioid infiltrations in anterior abdominal wall revealed with echosonography and the sizes of those found during the surgery. During the surgery, we discovered that parietal peritoneum was not involved in pathological process. Basing on our observations, we have made recommendations on formation of scar endometriosis risk groups. In all four cases, surgical treatment with succeeding course of hormone therapy resulted in recovery of the patients.