In this paper, adsorption isotherm of urokinase on two typical local diatomites were determined at 25 degreesC and their surface electrical potentials (zeta), isoelectrical point values (IEP) were determined. The properties of diatomites, the relationship among diatomite structure, pore-size distribution, surface and adsorption isotherm were discussed. The adsorption equation of urokinase was calculated from the adsorption isotherm. The adsorption mode of urokinase on diatomite surface was judged by the configuration function alpha. The relationship between the amount of adsorbed urokinase and IEP value was also discussed. (C) 2002 Published by Elsevier Science B.V.