Over the past twenty years a new class of microbial products, the microbial polysaccharides, has grown in industrial importance. These products can be used as alternatives to other synthetic or natural water soluble polymers or as novel polymers in thickening, suspending and gelling applications. In this article we review the technology of the production of extracellular microbial polysaccharides with particular emphasis on the characteristics and problems associated with handling highly viscous non-Newtonian culture fluids.