MORE than 25 years have passed since Kabat and co-workers,1using the Tiselius electrophoresis method, first noted that the cerebrospinal fluid (CSF) γ-globulin content was elevated in some patients with multiple sclerosis and neurosyphilis. Many methods have been described subsequently in the search for a rapid, simple, and reliable test which would quantitate the CSF immunoglobulins. The standard for accuracy for all these procedures has been the immunochemical method of Kabat et al.2Few clinical laboratories use this test, however, for it is time consuming, expensive, and complex. In 1966, a method of electroimmuno-diffusion (EID) suitable for use with minute volumes of unconcentrated CSF was described by Hartley et al.3It is the purpose of this paper to relate our clinical experience with this test, to compare it with other methods for quantitation of CSF immunoglobulins, and to summarize the available information regarding the value of CSF