The objective of the work is to summarize present knowledge on the health risk of nitrates and nitrates as a basis usable when evaluatiog the risk of nitrates from drinking water. It comprises four basic stages of risk estimation, i.e. hazard identification, hazard characterization of the danger, evaluation of exposure and characterization of risk. It deals also with an analysis of uncertainties associated with evaluation of the risk of nitrates in drinking water and draws attention to some hitherto not quite elucidated questions of possible chronic toxic effects of nitrates and their mediated carcinogenic effect. For the quantitative risk estimate the author recommends, with the exception of infants under 3 months, to use the WHO acceptable daily intake as a reference value, and attention is drawn to the increased risk of chronic toxic effects of nitrates in the child population. Based on the evaluation of health risks, the author recommends a cautious attitude of public health authorities when granting permission to use for drinking water with an above-limit nitrate content. He considers it justified to permit for drinking water with a nitrate content up to SO mg/1 but only in cases when another source of drinking water cannot be ensured and always only for a transitory period not exceeding 3 years. A basic prerequisite should be adequate information of the concerned population on the risk of nitrates with the recommendation to restrict the consumption of this water by pregnant women and children under 3 years.

        Key words: nitrates in drinking water - evaluation of the health risk