Poly (3,4-ethylenedioxythiophene)-(Poly(4-styrenesulfonate)) was synthesized on the surface of glassy carbon electrode by electrochemical method and used to determine biologically important L-dopa in the presence of a large excess of ascorbic acid by differential pulse voltammetry. The PEDOT-PSS surface was characterized by Scanning electron microscopy and ATR-IR. The oxidation peaks of L-dopa and ascorbic acid (AA) were well separated at PEDOT-PSS modified electrode in phosphate buffer solution (PBS, pH 7.0). A linear relationship between the peak current and concentration of L-dopa was obtained with the correlation co-efficient of 0.999 with the detection limit of 1.6 μM (S/N=3) in the presence of 5mM AA. The proposed method was successfully applied for the determination of L-dopa in pharmaceutical samples.