BACKGROUND: Plasmacytoid carcinomas are rare variants, and there are only a few reported examples of plasmacytoid carcinoma of the urinary bladder in the English-language literature. We now report another such case and the first in which there was examination of urinary cytology. CASE: A 79-year-old, Caucasian woman who presented with gross hematuria following a revascularization procedure on the right arm was found to have an extensive, diffuse carcinoma of the bladder. On biopsy, there were single, round and polygonal tumor cells with a striking plasmacytoid appearance infiltrating diffusely throughout the edematous lamina propria. Immunocytochemical stains confirmed an epithelial classification, and carcinoma in situ was demonstrated in the contiguous urothelium. Voided urine cytology before and after cystoscopy and biopsy demonstrated large, dyshesive tumor cells with plasmacytoid features. CONCLUSION: A case of plasmacytoid variant of urothelial carcinoma of the bladder is reported, with the first description of its urinary cytology.