In this study, a simple, rapid and accurate capillary electrophoresis method has been developed for the determination of lactulose and mannitol in urine for estimating the intestinal permeability. The urine samples were prepared to analyze by using solid phase extraction. For analysis a background electrolyte (BGE) consisted of 6 mmol/L sorbic acid, 1.25mmol/L hexadecyltrimeth ylammoniumbromide (HDTMA), 50 mmol/L LiOH (pH 12.5) was used. Separation was performed at -5 kV over 20 min within the fused capillary column (45 cm, 50 mu m I.D.) at 20 degrees C. The method developed was applied a series of urine sample to measure the lactulose/mannitol concentration rate.