Pathologists play an important role not only in diagnosing bladder tumors but also in reporting features important in determining prognosis, In this article, the authors review histopathologic features that may help determine prognosis including depth of invasion, grade of tumor, multicentricity, tumor size, and presence of (1) carcinoma in situ, (2) variant histological patterns, and (3) lymphatic and vascular invasion, The biology of bladder tumors is being extensively studied, and newer prognostic factors based on these molecular studies are emerging, some of which appear to show prognostic significance in limited clinical reports. Such factors as blood group antigen expression, proliferative indices, molecular markers, and new proposed techniques are discussed. Copyright (C) 1997 by W.B. Saunders Company.