In the presented work the effects of 3-years own investigations relative to technological usability of potato tubers of parental cultivar and its genetically modified clones were recapitulated. Potato tubers of cultivar Irga were transformed with viral genome sequences in order to improve their resistance to a necrotic strain of potato virus Y (PVY^N) at the Institute of Biochemistry and Biophysics, Warsaw, and tubers of the transgenic clones were produced at the Plant Breeding and Acclimatisation Institute, Młochów, in 2000-2002. At the first stage, the variability of parameters characterizing of raw material quality was determined. The characteristics of physical properties (size, shape, and mechanical resistance of tubers), microstructure, and content of main chemical constituents (starch, protein, ash, ascorbic acid, glycoalkaloids: α-solanine and α-chaconine) of 15 genetically-modified clones were investigated during three successive years. Tubers of these GM clones were next subjected to culinary processing (microwaving, cooking, and frying) and physico-chemical changes which are decisive for texture formation and texture properties of end-use product have been investigated and technological usability of GM potatoes was established. In this work, due to a considerable number of collected data, the final results were presented as means for modification group or, in two cases, as results relative to single clones representative for modification groups. Analysis of variability of physical and chemical parameters studied for the raw and heat-treated potato tubers enabled classifying Irga and its genetically-modified clones as similar, and did not allow distinguishing a clone of special usability for heat processing.