Bacterial Leaf Streak (BLS), caused by Xanthomonas vasicola pv. Vasculorum is an emerging disease threatening maize (Zea mays L.) production worldwide. The limited efficacy of chemical and cultural control methods necessitates the development of host-plant resistance as a sustainable management strategy. This study evaluated the agronomic performance and bacterial streak tolerance of eight maize genotypes released by the Institute of Agricultural Research and Training (IAR&T), Ibadan, under naturally infected field conditions. Maize seeds of each genotype were sorted into three size categories (large, medium, and small) and planted in a randomized complete block design. Data were collected on key growth and yield parameters, including plant height, leaf area, cob traits, yield components, and disease severity. Results revealed that all genotypes exhibited tolerance to BLS, with disease severity ranging from 0.80 to 1.60 and incidence between 2.33% and 6.67%. Large-seeded genotypes of ART-98-SW6, PRD-VIT-A, and ART-98-SW1 showed the lowest severity (<1.0), suggesting enhanced resistance, while small-grained variants were more susceptible. Yield performance varied among genotypes and seed sizes, with LNTP showing the highest total grain weight. Overall, seed size influenced both disease tolerance and yield potential, with larger grains conferring greater resistance to BLS. These findings highlight the importance of genotype and seed morphology in breeding strategies aimed at improving maize tolerance to bacterial streak under endemic conditions.