The objective of the experiment was to determine whether failure in polar fox reproduction may be related to diet quality. In two diets fed during the non-mating season on farm A having very good, and on farm B having very bad records, the contents of total and ileal digestible nutrients were determined. Diet A had a more diversified ingredient composition and higher contents of total and digestible dry matter and carbohydrates, total protein and ash. However, the ileal digestibility of dry matter, protein and fat was higher in diet B, probably because of its lower ash content.