Sesame (Sesamum indicum L) is one of the major oil crops with potential for production by small-scale holders in the marginal agro-ecological zones of Kenya. Variability studies on yield and yield components of sesame mutant lines now in M7generation was carried out in two locations for two seasons in Kenya. The objective of the study was to assess performance of the mutant lines developed through induced mutational breeding. According to mean performance, the thirty selected mutant lines and four check cultivars showed a wide range of genotypic variability for all the studied traits. Seed yield per plant registered the highest coefficient of correlation (63.8%). In addition, seed yield had positive and significant (P<0.05) correlation with biomass yield, harvest index and 1000-seed weight. It showed a weak positive association with plant height, oil content, number of capsules per plant and number of days to flowering. Biomass yield, harvest index, 1000 seed weight and oil content had positive direct effect on seed yield. Line Mun 096/1/k5/2/4 was superior to the best check cultivar Spssik 116.