The impact of high-frequency cross-flow back-pulsing on microsieves permeation performance during the microfiltration of whole milk is described in this work. Silicon nitride microsieves (0.8 mu m rectangular) combined with a dynamic permeate cross-flow back-pulsing technique to control fouling were used. Results showed that the transmembrane pressure (TMPpos) and the back-pulsing frequency were the process variables that most influenced microsieves performance. Permeation rates in the range of 5000 up to 27,000 L h(-1) m(-2) which are one order of magnitude higher than those reported for skim milk microfiltration were obtained depending on the process conditions selected. It was concluded that higher permeation rates are obtained when the back-pulse pressure, i.e., the negative TMP is set equal to the positive TMP, both at 150 mBar and the back-pulsing frequency at 15 Hz. (C) 2009 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.