Ten different Persian walnut cultivars were examined for their compositional data, including eight Hungarian and two introduced varieties. Oil content and fatty acid composition were determined, as well as oxidative stability (indicated by induction time). Antioxidative capacity, total polyphenol measurements, and individual phenolic compounds were also determined. Not only dry samples but fresh and stored samples were included in this study. Large differences were found among the varieties within these parameters, for example in oxidative stability, which contributes to antioxidative capacity. In conclusion, the nutritional value of Hungarian walnut cultivars was the same or even higher than those of foreign ones.