Nitrate ions are toxic pollutants. Their maximal allowable concentration in drinking and mineral waters is 50 mg/L. Most wells of Moldova contain high concentrations of nitrate ions. Thus, nitrate ion concentration monitoring in waters of Moldova is a very relevant issue. For determination of nitrate ions in colored water, the methods of choice will be the methods not compromised by sample color, e.g. chromatographic, capillary electrophoresis. These methods are expensive and involve special equipment. We suggest an indirect atomic absorption method of determination of nitrate by the excess of silver ions (after formation of the silver -1,10-phenantroline-nitrarate ternary complex). The indirect atomic absorption method of determination of nitrate is based on the formation of insoluble complex [Ag(Phen)2]NO3 when an excess of [Ag(Phen)2]+ is added to the nitrate containing sample. After separation of insoluble precipitate of [Ag(Phen)2]NO3 complex, the excess of silver ions is determined by atomic absorption method. Optimal conditions of atomic absorption determination of silver were found; the linear interval of calibration curves was set (correlation coefficient not less than 0.999). Metrological characteristics of methods were evaluated. The accuracy of determination of nitrate ion, carried out according to the suggested method, was evaluated by the standardized solution of nitrate ion with the concentration of 62.0 mg/L. The recovery was 96.8%. The variable error of the suggested method was evaluated as a variation coefficient, calculated for 10 measurements. CV (n=10) – 6.57%. The evaluation of the accuracy of determination of nitrate by the suggested method was also carried out using a real colored water sample by standard addition method. From 50mg/l introduced, 47.3 mg/l were recovered. The recovery was 94.6%.