Ethyl methane sulphonate (EMS) at different concentrations, viz., 0, 1, 2 and 3 mM/l, were used to induce genetic variability in three cultivars of potato, namely, Atlas, Nicola and Simon, for selecting mutants with increased level of resistance against early blight. Two hundreds and seventy plants per each cultivar were produced from M₀V₁ mutant generation. Each plant was evaluated, in terms of resistance to early blight, as compared to their original cultivar. EMS treatments induced genetic variation in potato genome which lead to new genotypes that displayed high levels of tolerance to Alternaria solani, and these genotypes may be considered new clones, Nine clones were selected; four from cv. Atlas, two from cv. Nicola and three from cv. Simon .Most of the selected clones were induced from 2 mM/l EMS  treatment. These clones are very important for disease tolerance and breeding programs due to their distinct features. DNA fingerprinting was done on the original cultivars and the selected clones using the RAPD technique. Genetic differences were detected between selected clones and the original cultivars.