Infection with gastrointestinal nematodes is a challenging and costly disease for sheep producers that impacts the economic efficiency of farms and reduces the welfare of infected animals. There is evidence that resistance to gastrointesti-nal nematodes is a heritable trait in sheep, and genetic selection for this trait is a novel method for Canadian sheep produc-ers to reduce levels of gastrointestinal nematode infection in their flocks. This thesis sought to identify functional regulatory elements including genes, mRNA isoforms, and long non-coding RNA that regulate the host immune response to gastroin-testinal nematode infection in sheep using hepatic tissue collected from animals with various levels of gastrointestinal nem-atode infection and immune responsiveness. A list of candidate key regulatory genes, mRNA isoforms, and long non-coding RNAs were identified. These candidate regulatory elements may be used in future genomic selection programs to increase the resistance of grazing sheep to infection by gastrointestinal nematodes.