Advances in fluidics, optics, electronics, lasers, computers and software have made flow cytometers considerably more complex, but also easier to use. Production of new fluorescent dyes has seen the development of more flexible instruments so that eight or more parameters of correlated data can be collected at once. Flow cytometers can be subdivided into two groups, analysers and sorters. A description of the commercially available analysers and sorters together with their specifications (as at October 1999) will be given.