Dead-end microfiltration of microbial suspensions is reviewed with particular emphasis on the factors affecting the specific cake resistance. The effects of cell size and shape, cell surface properties (including charge), ionic environment, fermentation medium components and ageing effects are reviewed in detail. The measurement of specific resistance and correlation of cake compressibility data is described and current understanding of the underlying mechanisms of cake compression is discussed. Factors affecting the packing arrangement of cells in filter cakes are also reviewed and discussed in the context of the Carman-Kozeny equation. (c) 2005 Elsevier B.V. All rights reserved.