In community-dwelling elderly men over age 70 years, BioE2 was positively associated with prospectively assessed BMD changes over 4 years. The CYP19 (TTTA)n-repeat polymorphism was, moreover, an additional independent determinant of BMD changes at the distal forearm. Furthermore, the CYP19 genotype was associated with self-reported clinical fracture status. The present analyses add further evidence to the view that serum BioE2 is a determinant of bone mass in elderly men and provides an indication that the aromatase enzyme may exert a direct modulatory action on bone metabolism at the tissue level in ageing men.