Abstract Most electrophoresis methods for separation of CSF proteins are generally preceded by some procedure of concentration and desalting of the specimen. Generally ultrafiltration techniques are used. The risk of losses, which may be unequal for different CSF proteins during such procedures, is to be stressed. On the other hand, desalting prior to isoelectric focusing (IEF) will minimized the curvature of the proteins bands, and in isotachophoresis (ITP) faster separation and increased capacity with repeated sample application are made possible. Since some years microdialysis of samples has been performed by the authors and found to be a valuable procedure both prior to IEF and ITP. With respect to microheterogeneity and recovery, tested by IEF, immunonephelometry and radioiodinated proteins no losses were observed. Ion exchange of acrylamide in a mixed resin, and recrystallization of bisacrylamide, were found necessary to avoid absorption from very dilute protein solotuins as CSF. Gel structure and perfomance were very dependent on polymerization conditions (time, temperature, initiator and accelerator concentrations).