We applied a sensitive silver nitrate stain to SDS-polyacrylamide gels to detect oligoclonal bands in unconcentrated CSF. Silver staining took less than 3 hours and gave easily readable bands in 93% of MS patients. In contrast, standard Coomassie Blue stain was positive in only 53%. Maximum resolution and numbers of bands resulted when silver staining was used on 10 to 20 microliters of CSF. Silver staining of SDS-polyacrylamide gels permits reliable oligoclonal band detection on small volumes of unconcentrated CSF.