The fine-needle aspiration biopsy (FNA) findings in a case of collecting duct (ducts of Bellini) carcinoma of the kidney are described. The cytologic smears were modestly cellular and contained individual and small clusters of round to oval cells with small to moderate amounts of well-defined cytoplasm. The nuclei were large and hyperchromatic with prominent single nucleoli and focal chromatin clearing. The findings were distinct from those of the usual clear or granular cell renal-cell carcinomas and were more similar to adenocarcinomas arising in the breast, ovary, or pancreas. Because collecting duct carcinomas need to be distinguished from metastatic deposits and are believed to have a poorer prognosis than the majority of renal-cell carcinomas, preoperative diagnosis may have important therapeutic implications. The distinction of collecting duct carcinoma from the more common variants of renal-cell carcinoma and transitional-cell carcinoma is discussed. Diagn Cytopathol 1994; 11:74–78. © 1994 Wiley-Liss, Inc.