Warfarin causes extensive vascular calcification leading to increased systolic blood pressure and pulse pressure in rats, may be associated with increased valvular and coronary calcifications in man, and possibly worsens hypertension in high-risk patients, particularly in those with diabetes mellitus or uncontrolled hypertension. The authors evaluated blood pressure and intensity of antihypertensive therapy over 36 months in a cohort of 58 patients with diabetes and hypertension on warfarin and 58 control subjects with diabetes and hypertension not on warfarin. The results demonstrate that warfarin therapy at conventional doses does not increase systolic blood pressure or pulse pressure in patients with diabetes and hypertension.