We hypothesized that patients with hemophilia or von Willebrand disease might be protected from atherosclerosis because of their coagulation defect. We studied 40 subjects affected by these two coagulation diseases using echocolor Doppler of the abdominal aorta and leg arteries, and compared the results with those obtained in 40 control patients who were homogenous with study patients in terms of sex, age, and risk factors for atherosclerosis. The probands presented a lower number of plaques than the 40 control subjects in the aorta and in the leg arteries. The most serious hemophilic patients had fewer plaques than controls or than patients with mild hemophilia. Both hemophilia and von Willebrand disease seem to protect against atherosclerosis.