A poly(indole-3-acetic acid) chemically modified electrode offers substantial improvements in voltammetric sensitivity and selectivity towards dopamine (DA). This polymer coating greatly attenuates the voltammetric response of ascorbic acid (AA) while the oxidation peak current of DA is enhanced by over an order of magnitude compared with that at the bare electrode. The high sensitivity and selectivity for DA appears to be mainly due to the charge discrimination and the analyte accumulation. The current response is dependent on both the solution pH and accumulation time. The detection limit is ca. 6.0×10−8mol/L. In 1.0×10−6M dopamine solution, AA shows no interference although its concentration is larger by 3 orders. The modified electrode is rather stable; a reproducible response of DA is obtained even after a month.