Endometriosis-associated intestinal tumors represent the malignant transformation of gastrointestinal endometriosis. Approximately 50 cases have been reported in the literature. They are most commonly found among women aged 30-60 years, whereas exogenous hormone therapy and obesity are primary risk factors for the malignant transformation of endometriotic lesions. Clinical features simulate a primary colonic carcinoma. A high index of suspicion in conjunction with careful histological and immunohistochemical examination (CK7, CK20, CDX2, CD10, ER, and PR) is important for establishing a correct diagnosis. In this article, a rare case of a postmenopausal woman with no risk factors and conflicting clinical presentation, diagnosed with endometriosis-associated intestinal tumor, is described.