An experimental study was made on the microfiltration of macromolecular solutions of guar and xanthan gums. The transmembrane flux was investigated using a laboratory unit equipped with a tubular ceramic membrane with a pore size of 0.6 mum. Experiments were conducted with transmembrane pressures of 300kPa, 400kPa and 500kPa and with tangential flow rates corresponding to the laminar and turbulent flow, respectively, in the Reynolds generalized number interval: 440-1000 (guar gum solution) and 3800-12000 (xanthan gum solution). Two gum solutions showed a polarization layer during microfiltration and the solutions' rheological behavior remained stable throughout the operation of the membrane and experimental pumping system. The analysis dimensionless is presented for correlations in the form: (J/u)(1/3) in function of DeltaP(tm)/rhoJ(2), and the results related to the Sherwood number were found to be compatible with the literature. (C) 2004 Elsevier B.V. All rights reserved.