A retrospective study was carried out at the Neurological and Neurosurgical Hospital of Lyon in order to evaluate the interest of detecting IgG oligoclonal bands by isoelectric focusing with IgG immunorevelation for the early diagnosis of multiple sclerosis (MS). Patients have been grouped according to their disorders: multiple sclerosis (281 cases), definite (182 cases) and possible (99 cases), others inflammatory neurological diseases (63 cases), various non-inflammatory neurological disorders (180 cases) and indefined neurological disorders (664 cases). The following examinations were performed: CSF cell count and cytology after concentration and cytocentrifugation, CSF and serum determination of albumin and IgG with CSF/serum ratios, agarose gel electrophoresis and isoelectric focusing of oligoclonal IgG. The technique used was isoelectric focusing using agarose gel, transfer onto PVDF membrane and then IgG immunorevelation with biotinylated anti-human IgG antibodies. Isoelectric focusing with IgG immunorevelation is the most sensitive (94%) and specific (96%) technique. Isoelectric focusing with immune detection can be recommended as the most efficient test (gold standard) for the detection of chronic CNS inflammation.