Lesions derived from remnants of the mesonephric (Wolffian) duct frequently occur in the wall of the uterine cervix and often cause diagnostic problems. Fifty-one cervical mesonephric lesions were studied. There were 40 lobular mesonephric hyperplasias and 11 diffuse mesonephric hyperplasias. Lobular hyperplasia was characterized by a distinctive clustering of mesonephric tubules, while diffuse hyperplasia was nonclustered. Fifteen patients with hyperplasia followed for a mean of 6.3 years were alive and well at last contact. In addition to morphologic differences between lobular and diffuse hyperplasia, there were statistically significant differences in patient age (means of 35 and 46 years, respectively) and lesion size (means of 11.8 and 15.7 mm, respectively), and less pronounced differences in proximity to surface epithelium and age-size correlations. Evidence suggests that the two types of mesonephric hyperplasias may be distinct entities. The morphologic appearances of the diffuse hyperplasias are emphasized to prevent their misinterpretation as variants of minimal deviation adenocarcinoma.