Among the cereals grown in Poland, oat grain contains the highest amount of ash, composed of macro- and microelements. It has been suggested that applying increased levels of mineral fertilization, to newer cultivars of oat could have an impact on their grain yield and mineral composition. A two-factorial (2x2) field experiment was conducted for three years (1999-2001) in the south of Poland. The experiment involved two cultivars of oat, i.e. the covered cultivar Dukat and the naked cultivar Akt, and two fertilization levels, i.e. low (30 kg N, 30 kg P2O5 and 45 kg K2O ha-1) and high (60 kg N, 60 kg P2O5 and 90 K2O ha-1). There was no significant difference in grain yield between the studied cultivars. On the other hand, the high NPK level increased the content of Mg and Fe in the grain of Akt. At the same time, there were no significant differences in the grain content of Cu, Fe, Mn and Zn between Dukat and Akt. Overall, the high level of mineral fertilizing decreased the grain content of microelements as a result of dilution effect. The content of Cu and Zn in oat grain was suitable for human consumption according to the IUNG-PIB standards. Generally, it was shown that cv. Akt was richer in mineral elements, especially in P, K, Ca, Mg, Fe and Zn, than cv. Dukat.