A stable electroactive thin film of poly(caffeic acid) was deposited on the surface of a glassy carbon electrode by potentiostatic technique in an aqueous solution containing caffeic acid. The electrochemical behaviors of acetaminophen on poly(caffeic acid) modified glassy carbon electrodes (poly(CA)-GCEs) were investigated by cyclic voltammetry and square-wave voltammetry (SWV). The results obtained that the poly(CA)-modified electrode was exhibited excellent electrochemical activity on the oxidation of acetaminophen. The calibration curve for APAP was shown two linear segments: the first linear segment increases from 0.2 to 1.0 and second linear segment increases up to 10 mu M. Using the first range of this calibration plot, a detection limit of 0.026 mu M is obtained for acetaminophen using square wave voltammetry. The poly(CA) electrode is selective not only for the detection of acetaminophen in the presence of ascorbic acid, dopamine, p-aminophenol and uric acid but also selective for the simultaneous determination of these four species present in a mixture. Finally, the proposed method was successfully applied to analysis of acetaminophen in pharmaceutical tablets.