A cohort of 270 superficial transitional cell bladder tumours (Ta-T1) was followed-up for over 8 years. WHO grade, papillary status and six nuclear factors were related to progression, recurrence-free survival (RFS) and bladder cancer-related survival (BS) during the follow-up period. Mean nuclear area (NA), standard deviation of nuclear area (SDNA), nuclear perimetry (PE), standard deviation of nuclear perimetry (SDPE), shortest nuclear axis ( D min) and longest nuclear axis ( D max) were significantly related to WHO grade and papillary status ( P < 0.0001). All the nuclear factors were related significantly to progression in univariate analysis ( P < 0.01) whereas in a multivariate analysis WHO grade ( P < 0.0001) and papillary status ( P = 0.048) included independent prognostic information. RFS was related to PE ( P = 0.009), SDPE ( P = 0.013), D min ( P = 0.021), D max ( P = 0.028) and SDNA ( P = 0.029). In papillary tumours SDPE ( P = 0.007) and D min ( P = 0.024) predicted RFS. BS was related to WHO grade, papillary status, NA, SDNA, PE, D max, D min (all P < 0.0001) and to SDPE ( P = 0.003). In papillary tumours PE ( P < 0.0001), D max ( P = 0.0022), D min ( P = 0.0027), WHO grade ( P = 0.0036), NA ( P = 0.0005), SDNA ( P = 0.0355) and SDPE ( P = 0.0718) predicted BS. In multivariate analysis SDPE ( P = 0.029) predicted RFS and survival was related to WHO grade ( P < 0.001) and PE ( P = 0.014) independently. In papillary tumours only D max ( P = 0.001) predicted survival independently. The results show that superficial papillary transitional cell bladder tumours can be efficiently categorised into prognostic groups by nuclear image analysis and the results provide a new classification system for superficial papillary bladder tumours. Tumours with high nuclear factor values should be considered for radical primary therapy and adjuvant therapy after transurethral resections.