In two studies including 73 patients the stress reducing effects of the tranquilizer Cloxazolam (Olcadil) and the beta-receptor-blocking drug pindolol (Visken) were investigated after the application of a single oral dose (3 mg Cloxazolam, 5 mg pindolol). The drugs were tested against placebo by the double blind method. After local anesthesia and during oral surgery an increase of dopamine-beta-hydroxylase (DBH)-activity, noradrenaline-, c-AMP-, ACTH and cortisol concentration was found in the placebo group. Cloxazolam antagonized all these effects, except the increase of the plasma levels of c-GMP under surgical stress. After pindolol noradrenaline concentration, DBH-activity, and c-AMP concentration were no longer increased during oral surgery. But the hypothalamic and adrenal stimulation were still present and resulted in an unchanged stress reaction of ACTH and cortisol concentration in plasma. In conclusion, the application of the beta-receptor-blocking drug pindolol prevents the stimulation of the sympathetic nervous system by suppressing the stress induced increase of plasma system by suppressing the stress induced increase of plasma noradrenaline and by blockade of peripheral beta-receptor sites. Cloxazolam reduces hypothalamic and adrenal reaction as well as peripheral ones due to stress.