An isotachophoretic method using polyacrylamide gel (PAG-ITP) in a simple disc electrophoretic equipment with plastic tubes containing the gels, was elaborated and especially designed for studying the gammaglobulins in CSF and serum from control subjects and patients with neurological disorders, especially known or probable MS. The device and the ITP system used, including leading and terminating electrolytes and spacer substances, dividing the gammaglobulins in a reproducible way, are described. No cooling of the gel tubes was needed. The sample volumes varied between 5--500 microliters, and the separation time was 1.5--3.0 h. CSF from patients with verified or probable MS revealed characteristic, increased low-mobility gammaglobulin fractions. Using other ITP systems, such as other spacer compositions, the anodic proteins can also be studied in more detail. PAG-ITP in gel tubes is a simple and inexpensive technique which can be used for both analytical and preparative procedures for biological material such as CSF, serum and extractions from nervous tissues.