Determination of dopamine (DA) in the absence and presence of ascorbic acid (AA) by ferrocenyl-tethered PAMAM G3 dendrimers (Fc-D) modified glassy carbon electrode (GCE) was reported. The modified electrode was characterized with cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Factors influencing the detection processes were optimized and kinetic parameters were calculated. The sensor exhibited excellent catalytic activities for the oxidation-reduction reactions of DA and eliminated the interference of AA. Under optimal condition, the linear range of 1 x 10(-5)-1.5 x 10(-3) mol L-1 and the detection limit of 4.7 x 10(-6) mol L-1 was obtained. This study provides a new idea for the determination of DA in the presence of AA.