A case of correcting duct carcinoma of the kidney is presented with hi
stologic and cytologic findings. Cytologic examination of voided urine
showed glandlike clusters of large cells with granular cytoplasm and
prominent nucleoli, along with normal transitional cells. Macroscopica
lly the kidney had a pelvic tumor mass that, on microscopic examinatio
n, was consistent with renal collecting duct carcinoma. Urinary cytolo
gy is useful as a diagnostic procedure evert in cases of rare entities
, such as collecting duct carcinoma.