A simple, fast and reliable spectrophotometric method was developed for determination of esomeprazole magnesium in pharmaceutical formulations. The method is based on the reaction of esomeprazole magnesium with bromocresol green, the formed ion pair complex extracted into chloroform at pH 3.5. The chloroform extractable layer is measured at 420 nm against reagent blank. Beer's law obeyed in concentration of 50-250 5g/ml of esomeprazole magnesium. The method is validated statistically.