['Post-ischaemic reactive hyperaemia in the forearm has been suggested as a marker of resistance vessel function. The contribution of forearm composition to the kinetics of reactive hyperaemia is largely unknown. The body composition of men and women differs in that women have a higher body fat content and less lean body mass.', 'In the present study, we investigated whether the kinetics of reactive hyperaemia in the forearm in 14 healthy subjects (seven men and seven women) show gender-specific differences and whether forearm composition contributes to such differences.', 'Peak reactive hyperaemic flow as well as 1-min-flow debt repayment (measured by venous occlusion plethysmography) were significantly higher in male than in female study participants. This difference was explained to > 60% by gender-specific differences in forearm relative muscle mass (as determined by magnetic resonance imaging). The half-life of the reactive hyperaemic response, on the other hand, was not different between men and women and did not show an association with forearm muscle.'] Does forearm composition contribute to differences in reactive hyperaemia between healthy men and women?