Primary ovarian carcinoid tumors are rare entities, they may appear with other teratomatous components, and can be often being mistaken as part of mature cystic teratomas. Consistent with their rarity and low incidence, imaging clues that could have led to suspicion of this tumor are not well-documented. Herein, the authors present a rare case of primary ovarian carcinoid tumor in a mature cystic teratoma, who initially presented with complaints of abdominal distension for months. Contrast-enhanced computerized tomography (CT) demonstrated a multilobular mass with different density components including fat, soft tissue, and calcification materials, as well as rich vascular supply from the right ovarian vein. Serum tumor markers were within normal limits. Bilateral salpingo-oophorectomy was performed and the pathological diagnosis was mature cystic teratoma with coexisting primary ovarian carcinoid tumor, insular type. The patient has remained well with no residual disease for over one year of follow-up.