Groundwater nitrate contamination has been a subject of concern because nitrate salts can induce infant methemoglobinemia and possibly human gastric cancer. In general, nitrates in drinking water may not be the main component of total nitrate intake, but nitrate-contaminated drinking water can make an important contribution to total nitrate intake. In this paper, a nitrate risk-assessment methodology is developed to assist decision makers in estimating human health risks corresponding to a particular nitrate dose to humans and in determining whether regulatory action must be taken to reduce the health risks. The case of a community with a nitrate water quality problem is used to illustrate the nitrate risk assessment methodology. The uncertainty associated with assessing health risks of nitrate and its impact on results are represented by using a fuzzy-set approach and incorporated into the nitrate risk assessment methodology. Therefore, a nitrate risk assessment can be made that is more realistic and appropriate than the one made without taking uncertainty into account.