Abstract: A study was undertaken on induced mutagenesis with CO1 and CO2 varieties of soybean. The mutagens studied were gamma rays (20, 30, 40, 50 and 60 kR) and EMS (5, 10, 15, 20 and 25 mM). In an assessment to fix the LD50 value, the varieties responded differently. A subtle difference was observed between the varieties CO1 and CO2 in the degree of tolerance to the mutagens, viz., CO1, (62 kR gamma rays, 26.4 mM EMS) and CO2 (58.3 kR gamma rays and 25.7 mM EMS). It is concluded that CO1 tolerate higher doses of gamma rays and EMS. In general, the treated population had manifested a reduced expression than the untreated population in all the biometrical traits. Reduction in phenotypic expression is linear with the dose or concentration of the mutagens in M1 generation. The mutagen gamma ray manifested higher percentage of reduction than EMS. In M2, EMS induced higher proportion of chlorophyll mutants than gamma rays. Among viable mutants, sterile mutant occurred more predominantly followed by stunted growth in both the varieties due to the effect of mutation. Induced mutations delivered fairly good amount of genotypic coefficient of variation, the heritability, GA as percent of mean with respect to number of seeds per plant, seed yield per plant and hundred seed weight for both the mutagen in both the varieties, indicating the scope for improving the soybean yield by selection. The mutants with four seeded pods, bold seeded types and increased number of pods per plant were isolated from this experiment.