Salivary duct carcinoma (SDC) is an uncommon and highly aggressive neoplasm that reveals histopathologic features resembling infiltrating duct carcinoma of the breast and prostate. SDC arising on the basis of preexisting pleomorphic adenoma (PA) is very rare. This report describes the fine-needle aspiration (FNA) cytology of a case of SDC ex PA. FNA smears were cellular with cells with large, pleomorphic nuclei, same prominent nucleoli, and finely vacuolated cytoplasm. The neoplastic cells were forming groups, sheets, and papillary structures and a cribriform patter-it was present in some sheets. Mitotic figures were frequently seen. Necrosis was prominent in the background. Histologic sections of the tumor revealed areas of comedo carcinoma, papillary carcinoma, and infiltrative carcinoma as well as multiple foci of PA. The presence of a cribriform pattern, tumor cells resembling breast ductal carcinoma cells, and a necrotic background are helpful features for an accurate cytodiagnosis of SDC. Diagn. Cytopathol. 1998;19:201-204. (C) 1998 Wiley-Liss,Inc.