Acinic-cell carcinomas and mucoepidermoid carcinomas remain somewhat controversial salivary-gland lesions. Because of an ambiguity in the literature concerning their malignant potential and a lack of sufficient follow-up periods, these carcinomas have been underestimated with respect to their morbidity and lethality. The failure of histopathologic evaluation to successfully predict the subsequent biologic course of these neoplasms should not mitigate treatment. Acinic-cell carcinomas are usually isomorphic neoplasms having their genesis in the neoplastic reserve cells of the terminal portions of the duct system. Mucoepidermoid carcinomas, on the other hand, may be described as forming a histologic spectrum or continuum from the most highly differentiated to the most poorly differentiated malignancy. They arise from the interlobular and intralobular ducts. The histopathologic features of these two neoplasms are presented, along with a review of their biologic activity in humans.