Current classification schemes for salivary gland neoplasms categorize cystadenocarcinomas on the basis of a recurring histomorphologic pattern of cystic, and often, papillary growth without features of other specific types of salivary gland tumors. To ascertain the clinicomorphologic spectrum and biologic behavior of this tumor, the clinicopathologic features of 57 cystadenocarcinomas from the files of the Armed Forces Institute of Pathology were studied. Excluding five Veterans Administration military cases, men and women were equally affected. Patients ranged in age from 20 to 86 years (mean, 58.8; median, 64), and patients aged over 50 years accounted for 71% of cases. Thirty-seven tumors (65%) occurred in major salivary glands, 35 in the parotid, and two in the sublingual glands. The 20 minor salivary gland tumors (35%) involved, in descending order, the lips, buccal mucosa, palate, tongue, retromolar area, and floor of mouth. Grossly, the lesions were cystic or multicystic masses that ranged in size from 0.4 to 6.0 cm. Microscopically, all tumors demonstrated an invasive, cystic growth pattern, and 75% had a conspicuous papillary component. The predominant cell type varied among tumors and included small cuboidal cells (35 cases), large cuboidal cells (nine cases), and tall columnar cells (seven cases). Six cases exhibited an admixture of cell types. Ruptured cysts with hemorrhage and granulation tissue were common. All 40 patients with follow-up data were either alive or had died of other causes and were free of tumor a mean interval of 59 months after their initial surgery. Three tumors recurred locally (mean interval, 76 months). Three tumors were metastatic to regional lymph nodes at the time of diagnosis, and one patient developed a regional lymph node metastasis after 55 months. Salivary gland cystadenocarcinomas represent a distinct group of malignancies that have an indolent biologic behavior.