The influence of 4 ml lidocaine 2% without vasoconstrictor, and with epinephrine 0.001%, or with norepinephrine 0.005% on the heart rate and blood pressure was investigated in one group of patients (n = 30) during a minor surgical procedure (tooth extraction) and in an age-matched group of volunteers (n = 30) with injection only and without any intervention. The difference between the 2 groups underlines the presence of emotional stress. Lidocaine without and with a vasoconstrictor changes the heart rate and blood pressure differently. These haemodynamic changes are superposed by alterations caused by emotional stress and are similar in all test series. The so-called epinephrine-collapse often seems to have its cause in an abrupt relative deficiency of epinephrine after stress. It is possible to significantly influence the cardiovascular system in connection with a local anaesthesia with the choice of vasoconstrictor.