This paper describes a high performance capillary electrophoresis method for the assay of inosine in oral tonic. The method employed a boric acid-borate buffer solution with SDS and UV detection at 254 nm. The capillary was 47 cm x 75 microm i.d.. Calibration curve shows good linearity. The recovery of inosine ranged from 95.0%-99.8% with a coefficient of variation (CV) of 2.4% (n=4). This method is simple, rapid and reliable.