In Great Britain, married couples were reported to have between 1.9 and 2.1 children, while men with Crohn's disease had a mean of 1.2 and of 0.4 children before and after diagnosis, respectively. The role of zinc for male fertility is essential. Although lack of zinc in Crohn's disease is well established in up to 70% of patients, a possible relation between zinc deficiency and male subfertility in Crohn's disease remains unclear. This study is aimed at examining a possible link between zinc deficiency in men with Crohn's disease and male subfertility in this group of patients.