Greengram is one of the most important pulse crops and important source of vegetable dietary protein acrossSouth and South East Asia. It also serves as an important green manuring and cover crop for enriching soil fertility due toits high atmospheric nitrogen fixation. Greengram suffers from several serious diseases, of which yellow mosaic virus,powdery mildew and Cercospora leaf spot cause considerable yield losses. Powdery mildew caused by Erysiphe polygonican potentially reduce greengram yield by more than 40% if there is no prevention or even cause death of the plants if itoccurs at the seedling stage. Therefore, initial efforts have been made to identify the resistant sources and to study thepolymorphisms between resistant and susceptible genotypes at molecular level. Six parental (Vigna trilobata, Vignaumbellata, SML668, Chinamung, DGGV2 and Selection4) and 54 F3 families were sown in field at MARS, Dharwad inkharif 2012. The percentage of leaf covered by the disease spores was scored visually. The percent was then translated intodisease rating scale and calculated percent disease index (PDI) and it ranged from 0 per cent for Vigna trilobata and Vignaumbellata to 95.06% for Selecion4. Of the six parental genotypes DGGV2, China mung and Selection4 were found highlysusceptible to powdery mildew with disease incidence of 95.06 per cent. Four cultivated (SML668, Chinamung, DGGV2,Selection4) genotypes along with two wild relatives (Vigna trilobata and Vigna umbellata) of greengram were used to studypolymorphism at molecular level using sixty RAPD and thirty three SSR primers. Out of 60 RAPD and 33 SSR primers,13 RAPD and 10 SSR primers were polymorphic. The value of similarity indices ranged from 0.165 to 0.632 for RAPDand 0.160 to 0.60 for SSR primers. The similarity between wild and cultivated varieties varied from 17.32 percent to30.43 per cent and between wild 54.62 per cent and among cultivated varieties similarity was up to 63.29 per cent. Thepolymorphic information content (PIC) refers to the value of a marker for detecting polymorphism within a population andit depends on the number of detectable alleles and the distribution of their frequency and equivalent to gene diversity. ThePIC value ranged from 0.45 to 0.67