Clark, W. D., Reyes-Valdes, M. H., Bond, J. and Kantartzi, S. K. 2013. Performance of LS97-1610בSpencer’ soybean recombinant inbred line population segregating for resistance toFusarium virguliforme. Can. J. Plant Sci. 93: 1179-1185. Sudden death syndrome (SDS) is a devastating disease in soybean which is caused by Fusarium virguliforme. Sudden death syndrome resistance is a quantitative trait; therefore, development of resistant varieties requires understanding of complex genetics and environmental effect. In this study, we aimed to characterize 94 F_5:8 recombinant inbred (RI) lines derived from a cross between a resistant line for SDS, LS97-1610 and a susceptible cultivar, ‘Spencer’ and to identify sources of resistance. The RI lines were evaluated for their relative resistance (RR) to SDS along with the parents in four different environments; two years (2009 and 2010) and two locations (Carbondale and Valmeyer, IL). Analysis of variance revealed significant interactions between genotype and environment in each year of experimentation and in 2-yr combined data. Broad-sense heritability was estimated by ANOVA results, and it was moderate (61%). These results indicate that SDS resistance is partially unpredictable due to environmental influence. Ten RI were identified to have a RR with no significant differences from LS97-1610 and two of them had a RR lower than resistant parent. These stable RI across environments were used for further evaluation in breeding programs. Additionally, data obtained from field evaluation can be used in combination with molecular data to study the effect of quantitative trait loci (QTL) with the environment. The identification of common QTL across environments with consistent expression is the ultimate goal of every marker-assisted selection program.