In 15 essential hypertensives resistant against a standard triple combination of antihypertensive drugs phlebotomy was performed. Mean arterial pressure was lowered from 140.1 +/- 12.2 mm Hg to 123.8 +/- 14.9 mm Hg after 14 days. No serious side effects were observed. The duration of the hypotensive effect of phlebotomy was about 4 weeks. Phlebotomy can be used in addition to drug treatment in resistant essential hypertension.