A new, sensitive method for determining dopamine has been established based on the principle of fluorescence quenching. A linear relationship is obtained between F(0)/F and the concentration of dopamine in the range of 0.80 -16.00 microg mL(-1). The detection limit was 0.23 microg mL(-1) and the relative stand deviation was 1.54%. The mechanism of the fluorescence quenching has been discussed. Effects of pH, foreign ions, and standing time on the determination of dopamine have been examined. This method is simple and can be used for the determination of dopamine in injections solution of dopamine. The results obtained by this method agreed with those obtained by the official method.