We demonstrate the possibility of a complete routine study on unconcentrated CSF from patients with Multiple Sclerosis (MS) using agarose isoelectric focusing (AIEF) followed by avidin-biotin-peroxidase complex staining to detect IgG oligoclonal bands (OB) and free light chains (FLC). The oligoclonal IgG patterns were demonstrated by loading the gel with only 225 ng of IgG. All the specimens were then diluted to a final concentration of 15 ng/L. The method also proved to be very sensitive for the detection of FLC patterns that were an interesting feature of the CSF from MS patients in active phases of the disease. The routine detection of abnormal IgG components synthetized inside the Central Nervous System (CNS) is really improved by the application of this method.