Cerebrospinal fluid (CSF) and serum IgG from 139 inpatients were analyzed for the detection of oligoclonal banding by isoelectric focusing on agarose (AIEF) with immunoperoxide staining. All of the patients had been admitted to one of the three major hospitals dealing with neurological diseases in Kuwait (Ibn Sina, Mubarak Al-Kabeer and Al-Amiri Hospitals). Of the 139 patients, 23 had oligoclonal bands in the CSF, 9 had evidence of intrathecal synthesis of IgG (bands in CSF but not in parallel serum), and 9 had evidence of systemic immune stimulation (oligoclonal bands in the CSF and in parallel serum). In 5 cases, serum was not available for an appropriate interpretation. Patients with intrathecal synthesis of IgG had demyelinating diseases and infections of the central nervous system (CNS). Patients with systemic immune response had infections, connective tissue disorders and malignancy. In cases with positive oligoclonal IgG in CSF, the diagnosis of diseases not associated with immune response within the CNS may be excluded. Our results compare favorably with already published sensitivity of AIEF and further recommend this method as a useful adjunct in the diagnosis of neurologic disease.