The aim of this investigation was to determine nitrate and nitrite content in potatoes from ecological and conventional farms. The influence of variety on nitrate and nitrite content was also evaluated. Vegetables and potatoes from ecological cultures are supposed to contain less nitrates and nitrites and on this basis could have been advised for children, sick and people in special physiological stages. Nitrite content was determined colorimetrically, with sulfanilic acid, nitrate content was determined following reduction of nitrites by means of metallic cadmium. The results showed significantly lower nitrate content in potatoes from ecological farms, and almost twice higher in those from conventional farms. The nitrite content showed no differentiation in conventional and ecological farms. Within three varieties of potatoes (sokół, bryza, ania) significantly highest content of nitrate was determined in bryza. Considering low nitrate level potatoes from ecological farms could be advised for children and sick people, but for the complete safety evaluation also content of other contaminants (i.e. heavy metals) have to be assessed.