Poly(acridine orange) was electropolymerised on glassy carbon electrodes by potential cycling in phosphate buffer solution at pH 5.5, 6.0, 7.0 and 8.0. Electrochemical behaviour of the modified electrodes was studied by cyclic voltammetry in phosphate buffer solution at various pHs and found that the best polymer film formation was obtained at pH 5.5. Quantitative determination of uric acid was achieved by cyclic voltammetry, differential pulse voltammetry (DPV) and fixed-potential amperometry in phosphate buffer solution at pH 5.5. Anodic peak currents were linearly proportional to concentration of uric acid in the range 1-75 A mu M for cyclic voltammetry, 0.4-75 A mu M for DPV and 0.04-5.3 A mu M for amperometry. Detection limits were 3.7 x 10(-1), 9.7 x 10(-2) and 9.5 x 10(-3) A mu M for cyclic voltammetry, DPV and amperometry, respectively. The modified electrodes exhibited good sensitivity, wide linear range and good stability. There is no interference from substances commonly present in natural samples.