Dry seeds of mungbean [Vigna radiata (L.) Wilczek] genotypes VC 2010 and Kawmy were exposed to two levels of gamma-rays 15 and 30 K.rad. Three generations M₁, M₂ and M₃ were studied after irradiation in the summer seasons of 1997, 1998 and 1999. The studied characters included growth parameters, yield, yield components and cytological behaviour.                 In the M₁ generation, it was observed that the radiation dose of 30 K.rad significantly reduced the rate of cell division than the control by 29% and 43% for the genotypes VC 2010 and Kawmy, respectively, and increased the appearance of chromosomal aberrations in mitosis in the two genotypes. It was observed that germination percentage, plant height, No. of branches per plant and No. of green pods per plant at harvest time (i.e., after 100 days from sowing seeds) exhibited significant reduction with increasing radiation levels in the two genotypes. While the number of mature pods per plant at harvest time, seed yield per plant and yield per feddan significantly increased by radiation with 15 K.rad in genotype VC 2010 while in Kawmy genotype these characters exhibited a significant decrease.                 In M₂ and M₃ generations, the following characters germination percentage, plant height, No. of branches per plant and No. of green pods per plant showed a significant decrease for both generations. However, the effect of radiation in M₂ and M₃ were less than in M₁ and the genotype Kawmy was more affected than genotype VC2010. The highest value of variability  was observed  in  the character  of  number of mature pods per plant for M₁, M₂ and M₃ generations, the lowest variability was recorded for germination percentage in all generations.