An alternative, simple, and reliable FIA amperometric method for ranitidine quantification was developed. A working glassy carbon electrode and a AglAgCllNaCI (3 M) reference electrode were used. The determination is based on the electrochemical oxidation of ranitidine at 1.2 V in phosphate buffer solution (pH 7.2). The determination of ranitidine in the range of 1 x 10(-6) to 2 x 10(-5) M was possible with a sampling frequency of 120 h(-1). The method was validated and satisfactorily applied to the determination of ranitidine in pharmaceutical formulations with a low limit of detection (6 x 10(-7) M) and a quantitative recovery with no interferences from excipients. The results compare favorably with those obtained by the liquid chromatographic method of the U.S. Pharmacopoeia.