Urine cytology from ureteral diversions utilizing intestinal segment as reservoir or conduit, constructed during cystectomy performed usually for advanced bladder neoplasia, differs from bladder urine cytology in that the presence of abundant intestinal mucosal cells with degenerative and inflammatory changes interferes with the recognition of other important cellular changes, particularly of recurrent neoplasia in the upper urinary tract, not to mention other less frequent yet note worthy pathologic changes, such as viral type indigenous to the urinary tract. When confronted with diseases involving the intestinal segment, such as viral enteritides, the diagnostic problem becomes more complex and special effort is needed to recognize and characterize them correctly, differentiating them from other pathologies or artifacts seen in such specimens. We report one such case in which viral changes affecting columnar intestinal epithelium were identified and by immunocytochemistry characterized as adenoviral involving primarily cells of the intestinal conduit. We discuss the significance of such infection in comparison to other viral changes indigenous to the urinary tract, which could also occur in such specimens. Diagn. Cytopathol. 2004;30:284–287. © 2004 Wiley-Liss, Inc.