The Invention relates to a method of predicting resistance to infectious pancreatic necrosis in salmon, the method comprising determining the alleles present at a DNA polymorphism in the salmon and predicting whether or not the salmon is resistant to infectious pancreatic necrosis based on the determination of the alleles. The invention also relates to a method of selecting a salmon for use as broodstock, wherein the salmon is selected based on the prediction by the first method that the salmon will have resistance to infectious pancreatic necrosis.