Abstract: The Mungbean Yellow Mosaic India Virus (MYMIV), transmitted through Bemisia tabaci causes severe damage in several grain legumes. Three mutant MYMIV-tolerant lines, namely, VM 1, VM 4 and VM 6, along with the susceptible Vigna mungo cultivar T9 were characterized. The objective of this study was to evaluate these three MYMIV-tolerant lines in comparison to the susceptible cv. T9 on the performance of eight agro-morphological traits. The four genotypes were grown in a randomized complete block design and combined analysis of variance over two years was carried out. The analysis of variance for individual years showed significant differences between these two genotypes for two traits in two consecutive years. However, combined analysis of variance over two years showed that except for few traits, there were no significant differences in other major traits amongst the genotypes. Genetic control of MYMIV-resistance was re-evaluated and confirmed a monogenic recessive nature. The molecular analysis revealed defect in the NB-ARC domain of putative disease resistance (R) gene in the susceptible cv.T9. While NB-ARC domains of all the MYMIV-tolerant mutant lines have common functional motifs. Presumably, the susceptibility of cultivar T9 is due to the limitation in transcript formation for the R-gene, which otherwise is a high yielding superior cultivar. Therefore, MYMIV-tolerant lines may prove useful to the plant breeders for further improvement towards sustainable agriculture.