Experimental results of cross-flow filtration of pseudo-plastic guar gum solutions are presented. We studied the variation in the rheological properties of a guar gum solution during a filtration run by recovering the layer remaining on the tubular membrane wall at the end of the run and by calculating the concentration at the membrane wall using the film theory model. The steady state fluxes were found to depend mainly on concentration and cross-flow velocity, while transmembrane pressure and pore size had very little effect. This is in agreement with the concentration polarisation mechanism, and the filtration rate seemed to be controlled by the dynamic membrane formed at the membrane wall. Besides, the flux rise with temperature was lower than expected from the permeate viscosity reduction. Finally, a first approximation of the boundary layer thickness, mass transfer coefficients and diffusion coefficient is given.