Ovarian carcinoid tumor is a rare neoplasm that may appear as a solid mass or often combined with teratomas or mucinous tumors. We report 2 cases associated with mucinous cystadenomas and describe their magnetic resonance imaging characteristics. On T₂-weighted images, the tumors appeared as multilocular cystic masses with hypointense solid components as a result of abundant fibrous stroma induced by serotonin. Demonstration of prominent hypervascularity of the tumors following contrast administration on dynamic study may be the clue to differential diagnosis.