O-aminobenzoic acid (o-ABA) film is deposited on glassy carbon electrode (GCE) by electropolymerization in pH 7.0 phosphate buffer solution (PBS). The polymeric film shows an excellent electrocatalytical activity on the oxidation of dopamine (DA). Difference pulse voltammetry (DPV) was performed to determine DA in an excess of ascorbic acid (AA). The oxidation peak potentials of DA and AA recorded are 144 mV and -52 mV, respectively. In pH 7.0 PBS, the anodic peak current of DA increases linearly over two concentration intervals, viz., 1.0x10(-7)-1.0x10(-5) mol L(-1) and 1.0x10(-5) - 2.0x10(-4) mol L(-1), with correlation coefficient, 0.9966 and 0.9960, respectively. The relative standard deviation of 10 successive scans is 2.8 % for 1.0x10(-6) mol L(-1) DA and the recovery is 96 % - 101 %. The interference of AA and DOPAC with the determination of DA could be eliminated because of the very distinct attracting interaction between DA cations and the negatively poly (o-ABA) film in pH 7.0 PBS. The proposed method exhibits good recovery and reproducibility.