Phenotyping of 76 bladder tumors (11 grade I, 33 grade II and 32 grade III) has been carried out by flow cytometry on cell suspensions with simultaneous determination of DNA content and surface immunofluorescence using G4 and 5 new monoclonal antibodies (10D1, 7C12, 6D1, 3C6 and 12F6) directed against bladder tumor cells. Ten normal bladder samples were used as control. Antibodies 6D1 and 12F6 were specific for tumor cells whereas the others also labelled umbrella cells. Cells from grade I tumors were labelled with 10D1, 6D1, 7C12 and 12F6 antibodies, and cells of grade II tumors with 7C12 and to a lesser degree with 12F6 but not with 10D1 and 6D1. Grade III tumor cells were specifically labelled with antibodies 3C6 and G4. Reactivity of antibodies with tissue sections was well correlated with cytometry results, except for the antibody 3C6. Finally, most of the cells stained by 3C6 and G4 were shown to have a DNA index greater than 1.0. In conclusion cells of low grade tumors can be identified with 10D1 and 6D1 antibodies, and antigens recognized by 3C6 and G4 antibodies are mostly expressed by aneuploid cells.