Ascites is commonly observed in broiler chickens where increased pulmonary vascular pressure results in the accumulation of large amounts of fluid in the abdominal cavity of the birds. Ascites is a commercial concern for the poultry industry resulting in significant losses world wide. In a genome-wide SNP survey of an F2 cross of ascites resistant (RES) and susceptible (SUS) lines, we identified 9 chromosomal regions that showed Linkage Disequilibrium (LD) with respect to ascites susceptibility and ventricular hypertrophy. We validated five of these regions using VNTR (Variable Number Tandem Repeats) genotyping tests to confirm segregation distortion in a larger sample from the SUS line. Three of the validated regions contain genes affecting the serotonin and angiotensin response pathways, genes that have been associated with pulmonary hypertension in humans. Resequencing from the RES and SUS lines has identified Single Nucleotide Polymorphisms (SNPs) in these candidate genes. SNP analysis of additional samples from our experimental lines and commercial lines, have confirmed the association of these regions with ascites phenotype in multiple lines. We are examining expression of these candidate genes in different tissues. In addition we are correlating genotype for some of these regions with production traits, to assess the connection between broiler selection and ascites susceptibility.