Extrapulmonary small cell carcinoma is a rare neoplasm. It is a highly aggressive, malignant tumor with rapid local progression and early metastasis. We report a case of small cell carcinoma arising in the rectum that presented as a bowel habit change in a 57-year-old man. Physical examination revealed a firm, fixed mass in the rectum. Computed tomography of the mass revealed a circumferential bulky mass with an irregular margin with perirectal fat infiltration and enlarged regional lymph nodes. Histologic examination of the resected mass was consistent with small cell carcinoma of the rectum.