In 40 patients with idiopathic systemic hypertension, skin blood flow was evaluated with laser-Doppler flowmetry, transcutaneous measurements of partial pressure of oxygen (PO2) and partial pressure of carbon dioxide (PCO2), and determination of capillary permeability before and after treatment with nifedipine (10 mg tid for four weeks). Also 35 normal subjects matched for age and sex distribution were studied. Before treatment, microcirculatory studies showed a significant decrease in skin flow and venoarteriolar response in hypertensive patients in comparison with normal subjects. Moreover, PO2, PCO2, and capillary permeability were significantly lower in hypertensives. All these microcirculatory parameters significantly increased after nifedipine treatment while both systolic and diastolic pressures decreased. In conclusion, laser-Doppler flowmetry used with other microcirculatory techniques was able to discriminate between normal subjects and hypertensive patients, and it was able to show the improvement in the microcirculation after nifedipine treatment.