Groundnut is an important oilseed legume crop cultivated all over theworld. Due to less genetic diversity, autogamous nature, small flowersand ploidy difference between cultivated and wild relativesconventional breeding approaches to improve yield has not resultedin desired level of yield improvement. In such condition mutationbreeding can be used as promising tool to create variability. TMV2, apopular, old variety of groundnut, was selected for this study as it ishighly accepted by farmers and traders for its desirable agronomicand quality features. Dry and well filled seeds of TMV2 were treatedwith chemical mutagen EMS (Ethyl methane sulphonate) at variedconcentration viz., 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8 and 0.9 per centto study the effect of mutagen on germination percentage in laboratoryconditions. This experiment was conducted during kharif 2017 atZAHRS, Shivamogga. The data on germination percentage wassubjected to probit analysis (Finney, 1971) and lethal dose (LD50)was 0.3 per cent.