Abstract: ICP-MS was applied to the determination of bromine and iodine in waters.The water sample was diluted with internal standard solution and determined directly without any pretreatment.Aqueous ammonia solution (1+99) was used both as the medium and washing solution in the determination.Indium ion was used as internal standard.Linear relationships between values of intensity of response signal and mass concentration of bromine and iodine were kept in the same range within 100 μg·L-1 with detection limits of 0.19 μg·L-1 for bromine and 0.083 μg·L-1 for iodine.Precision of the method was tested at the concentration level of 5 μg·L-1 mixed standard solution for 18 determination,values of RSD′s found were 2.3% and 1.9% for bromine and iodine respectively.The proposed method was applied to the analysis of water samples,giving values of recovery in the range of 88.0%-110%.