• Mixed tumors are unusual in that they possess both epithelial and mesenchymal elements. The proportions of the two elements vary greatly; the lesions with a pronounced preponderance of epithelial tissue have been called cellular mixed tumors. This increase in epithelial cellularity often results in misdiagnosis or in concern that the tumor may be more aggressive than the ordinary mixed tumor—possibly even malignant. We have reviewed 1,095 consecutive parotid tumors that were removed at the Mayo Clinic, Rochester, Minn, from 1950 through 1970. Ninety-three of the lesions were diagnosed initially as cellular mixed tumors, and slides were available for review. Of these 93, 43 fulfilled our criteria of having greater than 80% of each tumor composed of the packed epithelial cells. All tumors had a corresponding reduction in the mesenchymal portion. The records of the 43 patients were studied to determine the clinical behavior of these neoplasms, particularly with regard to recurrence, metastasis, and malignant transformation. Our findings confirmed our clinical suspicions that some of these cellular mixed tumors, notably those that showed histopathologic evidence of an increased rate of mitotic activity, can and do act in a more aggressive manner. (Arch Otolaryngol 104:451-453, 1978)