A case of primary carcinoid tumor of the ovary producing the carcinoid syndrome is reported. Microscopically, the tumor was pure, and not associated with other teratomatous elements. Ultrastructural examination revealed the characteristic polymorphic secretory granules situated in the basal portions of the tumor cells, similar in morphology to the granules commonly seen in tumors of midgut derivation. The literature on carcinoid tumors of the ovary is reviewed. Including our case, there are 47 documented cases of primary carcinoid tumors arising in the ovary, of which half have been associated with the carcinoid syndrome. Twelve of the reported cases are of the pure type and not associated with other teratomatous elements. Only three cases of malignant carcinoid tumors with metastasis have been reported.