The purpose of the study was to determine the effects of different N rates used for fertilization of four potato varieties on nitrate content of potato tubers. In addition the aim of the study was to define changes in nitrate content of potato tubers during culinary process. The experiments were conducted on four potato varieties – Bard, Lord, Cedron and Kuba. The experimental field with Bard and Lord varieties was fertilized with three N rates: 40, 80 and 120 kg of N·ha^-1, while Cedron and Kuba varieties were fertilized with two N rates: 100 and 140 kg of N·ha^-1. From potato fertilized with basic N rates (40 kg N·ha^-1 for Bard and Lord varieties and 100 kg N·ha^-1 for Cedron and Kuba varieties), potato samples were taken peeled handly and analysed before and after cooking. The measurements of potato tubers included: dry matter, starch (except cooked potatoes) and nitrate content. The varieties destined for cooking exhibited lower dry matter and starch content, but higher nitrate content than potato varieties destined for chips and dehydrated products manufacturing. Higher N rates affected in higher content of nitrate in potato tubers, and edible potato varieties to a larger extend reacted on mineral fertilization. Culinary processes decreased nitrate content – peeled potatoes contained 20%, and cooked potatoes contained 30% lower nitrate amount.