A capillary electrophoretic method for the determination of lansoprazole in pharmaceutical preparations is described. The analysis was performed in a fused silica capillary using 20 mM borate buffer at pH 8.7 as a background electrolyte. The best resolution was obtained by applying a potential of 30 kV and vacuum injection of 1 s. Detection was made of 200 nm. Phenobarbital sodium was a good internal standard and the migration times were 4.1 +/- 0.2 min (lansoprazole) and 5.7 +/- 0.2 min (phenobarbital sodium). A well-correlated calibration equation was found in the range of 1.12 x 10(-5) and 2.24 x 10(-4) M. Limit of detection (LOD) and limit of quantitation (LOQ) were 1.4 x 10(-6) M (RSD 1.44%) and 4.42 x 10(-6) M (RSD 1.49%), respectively The method was validated and applied to the capsules containing enteric coated pellets of lansoprazole. The results of the proposed method were compared those of UV spectrophotometry Insignificant differences were found between the two methods at the 95% probability level, The described CE method is selective, rapid, sensitive and accurate for the analysis of lansoprazole in quality control laboratories.