Abstract: Nitrate levels in oat at three different regions within the country were determined. In this case the factors that can affect the accumulation of nitrates in pastures are analized, as well as the correlations between nitrate levels in oats, nitrate levels in the soil, previous fertilization with nitrogen-containing compounds and pertinent meteorologic data. The nitrate levels in soil were studied using a potentiometric method with a specific electrode. Tau coefficient of correlation was used for studying the association between nitrates in soil and nitrates in oats. The significance level was established at 0 0,05. The statistical program SPSS was used for analizing the results obtained. In none of the places analized (San Jose, Paysandu and Canelones) the nitrate levels in soil correlated positively with the nitrate levels found in oat. The only oat sample that reached potentially toxic levels correlated with a high level of nitrate in soil. All of the samples analized had received nitrogenated fertilizations before sowing. There was no hydric deficit previous to any sampling which coincides with the low levels reached during the determinations.