In 28 aged patients (means = 73.1 years) with arterial hypertension nifedipine has been administered sublingually in a single dose of 20 mg and the hypotensive effect of that drug under the control of its concentration in the blood serum was evaluated. The nifedipine concentration was determined by the use of gas chromatography with electron capture detector. The mean drug concentration increased from 38.1 ng/ml to 82.3 ng/l during the 2nd hour of observation. After 3 hours the lowering of the nifedipine concentration and the decrease of its hypotensive effect was observed. After 15 min from the drug application the systolic pressure lowered by the average 22.1 mmHg whereas the diastolic pressure was 7.0 mmHg lower. The most significant pressure decrease (mean of systolic pressure 52.7 mmHg) 7.03 kPa and that of diastolic pressure 23.2 mmHg (3.1 kPa) occurred after 2 and 1.5 hours. The decrease of pressures after nifedipine correlated with the start-point value of systolic pressure. The frequency of the heart action in the whole group did not altered significantly, however, in individual cases both the acceleration of that action (34 per min) or acceleration (42 systoles per min) was noted. Slight typical side-effects were noted in 5 treated patients. A single-dose sublingual 20 mg nifedipine (Cordafen--Polfa) administration enabled in all the subjects the obtaining of therapeutic drug level in the blood and in the aged patients with hypertension may be regarded as efficacious antihypertensive treatment.