We attempt to examine to qualitative comparison of plasminogen activator (PA) in transitional cell carcinoma of the urinary bladder and normal bladder mucosa as control. PA was purified by three procedures of 30% ammonium sulfate precipitation, acid treatment and concanavalin A-Sepharose affinity chromatography. Purified PA was analysed by using electrophoretic enzymography, fibrin film method and chromogenic substrates (s-2444 and s-2288) reaction. Purification factor of PA from bladder tumors (tumor PA) and PA from normal bladder mucosa (normal PA) was about 80, 000 and 325, 000, respectively. Enzymography revealed that tumor PA adsorbed to concanavalin A-Sepharose showed a single lytic zone at 55, 000 and normal PA adsorbed to the same column 72, 000. Both PAs lost fibrinolytic activity in the absence of plasminogen. The PA activity was inactivated by DFP. Tumor PA reacted with anti-UK IgG but not with anti-t-PA IgG. On the other hand, normal PA reacted with antit-PA IgG but not with anti-UK IgG. Both PAs cleaved s-2288 to a greater extent than s-2444, although UK cleaved s-2444 to a greater extent than s-2288. So both PAs were thought to show t-PA type amidolytic activity.