The present research was carried out to study the effect of using gamma rays dose 10 and 15Kr on the yield and yield components and quality traits in M₁, M₂ and M₃ generations during 2014, 2015 and 2016 seasons for two cultivars Giza 92 and Giza 94. The results showed that the effects of treatment were significant for all studied traits except Micronaire reading in M₁ and fiber length in M₁ and M₂. Also the results revealed that the interaction between the cultivars and doses were significant for all traits except for boll weight in M ₃, lint percentage and fiber length in M₂. The effect of dose 15 Kr had significant effects for seed and lint cotton yield. The variability in M₁ and M₃ were higher than the variability in M₂ due to effectiveness of sever selection in M₁ generation. Positive coefficient skewness were found for seed cotton yield, lint yield, number of bolls and lint percentage indicating that most of plants lie left half of curve. While, most of plants lie in right half of curve for boll weight, Micronaire reading and pressely index in M₁. Moment coefficient of kurtosis were less than 3 for all traits in M₁, M₂, and M₃ it can be concluded that the normally curves of plant distribution were platykurtic so the variabilities were broad.