For the first time, we report a case of an inflammatory pseudotumor of the sigmoid colon originating from an infection with Enterobius vermicularis. A 42-year-old man presented with left lower abdominal pain, weight loss, fever, nausea, and vomiting. Physical examination revealed tenderness and a palpable mass in the left lower quadrant. Laboratory results demonstrated elevated leukocyte count. Colonoscopy showed 25 cm above from the anus a nonobstructive, approximately 4 x 4 cm irregular lesion narrowing the sigmoid colon lumen with erythematous and rough mucosa; a diverticulosis could not be observed. Colonoscopic biopsy showed inflammatory changes. Computerized tomography (of the abdomen showed a 10 x 6 x 6 cm mass at the left lower abdomen. On abdominal exploration, the mass in the sigmoid colon was detected, and anterior resection of the sigmoid colon was performed. Histopathologic examination of the specimen revealed eggs of the E. vermicularis embedded in the granulation tissue and in the submucosa/mucosa of the sigmoid colon. The patient was uneventful in the postoperative period and discharged 7 days after surgery.