The gamma rays treated seeds of four mungbean varieties (V1=NM-98, V2= KM1, V3= Inqilab mung and V4= Sona mung) were studied for both biochemical and molecular analysis. Randomized Complete Block Design (RCBD) was used for the experiment with four treatments using three replications (T0= Control, T1= 5 krad, T2= 10 krad, T3= 15 krad and T4= 20 Krad). Maximum biochemical and molecular based variability was recorded among genotypes. Higher amount of total sugar and proline contents were recorded in the plants grown from the seeds treated with T1, T2, T3 and T4 as compared to the control (T0) plants. On the other hand, effect on the protein content was inversely proportional to the increasing range of the radiations i.e. in T4 treated plants the protein content was low in comparison to the T3, T2, T1 and T0, respectively. However lower protein content was recorded in all treated samples with increasing of gamma radiation doses. The Random Amplified Polymorphic DNA (RAPD) primers were used to check molecular based variability in the allelic pattern at different gamma irradiation treatments. The three primers (OPS-03, OPB-1 and B-11) amplified four extra alleles in treatments), KM-1 (after T2, T3 and T4 treatments), Inqilabmung (after T1 treatment) and Sonamung (after T2, T3 and T4 treatments). Variations in physiological, biochemical and more interestingly the molecular (amplification of extra alleles/bands) attributes of the treated plants grown could possibly be due to the changes in the genome of these varieties. However, this study serves as a model to check the effect of gamma rays on other economically important crop species.