Bacterial cold water disease (BCWD) is one of the frequent causes of elevated mortality in salmonid aquaculture. Previously, we identified and validated microsatellites on chromosome Omy19 associated with QTL (quantitative trait loci) for BCWD resistance and spleen size in rainbow trout. The objective of this study was to identify single nucleotide polymorphism (SNP) markers associated with BCWD resistance and spleen size using both genome-wide association studies (GWAS) and QTL mapping approaches.