The clinical and pathological features of five personally observed ovarian myxomas and three similar tumors previously described in the literature are analyzed. The patients' ages ranged from 16 to 45 years (mean, 33 years). An asymptomatic unilateral adnexal mass was the usual presentation. The tumors were 5 to 22 cm (mean, 11 cm) in greatest diameter, intraovarian, solid, and cystic, and they were occasionally blood-filled. None had ruptured. The intercellular matrix contained abundant hyaluronic acid in each of the five personally observed cases. The tumor cells were immunoreactive for vimentin and usually for actin, but not for desmin, S100-protein, neuron-specific enolase, neurofilament, Leu-7, epithelial membrane antigen, keratin (AE1/3, CAM5.2, MAK6), or factor VIII-related antigen, and did not bind Ulex europaeus agglutinin 1. Vascularity was a notable feature on microscopic examination. All the patients were treated by a surgical procedure alone, usually a conservative operation, and none of the five tumors with a follow-up period of 1 to 13 years (mean, 5 years) recurred. The ovarian myxoma is a distinctive type of ovarian neoplasm that should be distinguished from massive edema, edematous fibroma, and myxoid sarcomas.