A micro-method for the identification of most acidic mucopolysaccharides by agarose gel electrophoresis with three different buffer systems is described. In barbital buffer the mucopolysaccharides are fractionated from each other as a function of their net charge, whereas in a diamine buffer the fractionation is probably achieved according to the degree to which they are bound to the diamine. A combination of barbital and diaminopropane buffers in two-dimensional electrophoresis for the identification of mucopolysaccharides is also described.