Background: One of the important characteristic features of the new antihypertensives drugs is its 24-hour effectiveness. If the drug reaches the mean trough/peak over 50% it can be dosed once daily. The pulse pressure (PP) increases with the age and correlates better with the organs damage and with the cardio-vascular disease and mortality of hypertonic patients, than the systolic or diastolic pressure itself. The optimal values of PP have not been known yet in various age categories and patients with other associated risk factors and diseases. Methods: Blood pressure (BP) measurement using 24-hour ambulatory blood pressure monitoring (ABPM) (SPACELAB 90207) and mercury sphygmomanometer (Germed ) according to the WHO criteria. For the peak value we used the mean BP from the 3rd - 6th hour after the using of betaxolol hydrochloride or placebo, for the trough value the mean BP from the 22nd - 24th hour of the measurement was used, 30 minutes after getting up in the morning and excluding the influence of the hospital surroundings. The programme Statistica for Windows 98, StatSoft, Tulsa, was used for the statistic evaluation. We evaluated 50 patients with newly diagnosed essential hypertension mean age 39 + 10 years before and after the 3months of treatment with 20mg betaxolol hydrochloride once daily. Results: 1. Trough/peak ratio betaxolol hydrochloride is 70% by the systolic BP, after correction to placebo 80%, and it is 71% by the diastolic BP after correction to placebo 78%. 2. The results of PP measurement are: office PP befor treatment 47,8 mmHg, after 43,2 mmHg, P below 0,001, 24h ABPM PP befor 47,3 mmHg, after 46,5 mmHg, P = 0,08*, Day ABPM PP before 47,8 mmHg, after 46,3 mmHg, P below 0,005, Night ABPM PP before 46,3 mmHg, after 46,7 mmHg, P = 0,56*. (* statistically not significant differences). Conclusions: 1. Betaxolol hydrochloride has the value trough/peak over 70% and it can be dosed once daily. 2. The mean age about 40 years characterises younger individuals with the lower mean value of PP and lower potential adverse cardiac implications. 3. The fall of mean office and day ABPM PP values is caused by the time of the measurement. The morning and fewer the afternoon BP and PP were the highest and the highest betaxolol hydrochloride effect was after the treatment. It was seen the less fall of PP in the night hours.