The patient described synchronous mucinous tumors of the cervix and ovary and concurrent annular tubules, but without the classical stigmata of Peutz-Jeghers syndrome. The cervical tumor was an invasive mucinous adenocarcinoma with mixed components of minimal deviation and less-well-differentiated endometrioid morphology. The ovarian tumor had the benign appearance of a mucinous adenoma but histologically revealed areas of invasive carcinoma. Immunohistochemical studies of the mucinous neoplasms of the cervix and ovary are discussed. Neither the staining properties of mucin, the pattern of immunostaining for carcinoembryonic antigen, nor any other common markers were helpful in distinguishing the mucinous neoplasms. Positive immunostaining for low-molecular-weight cytokeratin in the filament profile of sex cord tumors with annular tubules was of particular interest since it has not to our knowledge been previously described.