A new method for flow injection analysis of norepinephrine bitartrate has been developed. It is based on ion association with anionic surfactant and piezoelectric detection. Sodium dodecyl phenylsulfate was used as the ion association reagent. The calibration curve was linear between 0.01 and 1.20 mg/ml. with a detection limit of 5 μg/ml, a relative standard deviation of 0.18% (10 replicates) and a sampling frequency of 120/h. The proposed method has been satisfactorily applied to the determination of norepinephrine bitartrate in pharmaceutical preparations.