The contemporary classification and grading of human papillary urothelial neoplasms remains unsettled, with multiple recent suggestions by groups of pathologists with little or no clinical input. One of the chief motivations for these new approaches was to avoid use of the term "cancer" for neoplasms with a low likelihood of invasion, recurrence, and death. Also, critics contended that earlier grading schemes were too imprecise to be clinically useful. We summarize the work carried out by the majority of members of Committee No. 1 at the International Consultation on the Diagnosis of Non-Invasive Urothelial Neoplasms held in Ancona, Italy (11-12 May 2001). Our deliberations represent a multidisciplinary international effort based on the best available data and the perception of existing practical methods of classification by clinicians, pathologists, and cancer registrars. The WHO 1973 classification for papillary urothelial neoplasms (papilloma, grade 1, grade 2, and grade 3 carcinoma) is still superior to all existing alternatives (such as WHO/ISUP 1998 and WHO 1999), although some refinement of diagnostic criteria would be useful. Some pathologists may prefer additionally to report synonymous classification in other schemes, but this is discouraged owing to variations and difficulties in translations.