A novel voltammetric method using a new carbon electrode has been developed for simultaneous measurement of any combination of nitrite ion (NO2-), dopamine (DA) and serotonin (5-HT) with ascorbic acid (AA). Both cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used for measurements of the neurotransmitters by means of a GRC (graphite reinforced by carbon) electrode in phosphate buffered saline (PBS) solution (pH 7.3). Anodic peaks of DA, 5-HT and NO2- with AA were observed at 0.17, 0.35 and 0.85 V vs Ag/AgCl on the DP voltammogram, respectively. A linear relationship was found between the DA concentration and the peak height on the voltammogram in the range of 1-20 micro mol dm(-3) (mu M) DA, even in the presence of 10 mu M 5-HT, 50 mu M NO2- and 0.2 mM AA. A linear relationship was similarly found for 5-HT in the range of 1-20 mu M with 50 mu M NO2- and 0.2 mM AA, and it was also found for NO2- in the range of 5-200 mu M with 10 mu M DA and 0.2 mM AA. These results showed that the method was quite effective not only to detect DA, 5-HT and NO2- even in the presence of AA, but also to determine simultaneously the concentration of each content.