To describe the clinical, pathologic and immunohistochemical characteristics of collecting duct carcinoma (CDC) of the kidney.Five cases of CDC (3 males and 2 females, aged 41 to 67 years) were identified between January, 1990 and December, 1994. Routine histopathologic study and immunohistochemical examinations of the surgical specimens were performed.Four patients underwent radical nephrectomy; 3 have been alive without evidence of recurrence for 3 months, 2 years and 2.5 years, respectively after the operation. Bone metastasis was noted 2 months after the operation in 1 case. One patient was submitted to simple nephrectomy because of extensive regional node involvement and died of lung metastasis 14 months after the surgery. Grossly, the tumors were usually grey-whitish in color and located in the renal medulla. Microscopically, the characteristic structure of tubulo-papillary pattern could be identified. Marked desmoplastic reaction was noted and atypical hyperplastic changes were found in the adjacent collecting ducts. Immunohistochemical studies revealed positive results to epithelial membrane antigen, high molecular weight cytokeratin and peanut agglutinin.CDC of the kidney is a rare disease with a poor prognosis. Radical nephrectomy is recommended even if the tumor is small.