ABSTRACT.- Ergot disease (Claviceps paspali) and sterility have the potential to reduce seed yield in bahiagrass (Paspalum notatum Fluggé). Our objective was to determine the genotypic and environmental effects on seed yield, and the levels of ergot and sterility. Seventeen genotypes were evaluated in three locations across two years for seed yield, ergot severity, and total seed fractions (percentage of full seeds, ergot sclerotia and empty seeds). The percentage of full seeds and total seed yield were correlated (r = 0.52) but both were negatively correlated with the percentage of ergot sclerotia (r = -0.81 and -0.51). Empty seeds were negatively correlated with full seeds (r = -0.39), but not with ergot sclerotia and total seed yield. The genotype effect was significant for total seed yield and severity of infection with large heritabilities (H2 = 0.92 and 0.86) but had no effect on the percentage of the seed fractions. Location and the interaction with genotype explained most of the variation in the percentage of the seed fractions and their weight. Ergot and sterility were significant detrimental factors, genotype was a major determinant of ergot levels and seed yield, while non-genetic factors were co-determinants in constructing the seed yield potential but were the main determinants of the yield potential realization. Copyright: © 2023 by the authors.