15 samples of potato tubers of Irga cultivar subgroups transformed with viral genome sequences (two modifications in the sense and antisense positions) in order to improve their resistance to a necrotic strain of potato virus were examined and compared to Irga tubers cultivated under normal and in vitro conditions during 3 successive years. The average weight and tuber weight distribution, and size and shape features (length, width and thickness, shape coefficient, and equivalent diameter) of tubers were measured using traditional and digital image methods. Tubers of the examined clones were classified as roundish/longish, except for longish/long tubers of two clones: R2P and R2Y. The variability of tuber shape, related to its size, for three modification subgroups was similar to constantly roundish Irga tubers, while tubers of only one subgroup were similar to Irga w.t. tubers, whose bigger tubers were more oblong. Then, it can be concluded that genetic modifications of Irga potatoes did not affect permanently the size and the shape of tubers, neither a for single clone nor for clone groups in modification subgroups. The year of cultivation and seed preparation were factors significantly affecting the weight, size, and shape of tubers of normal and genetically modified potatoes.