The local use of adrenalin is a standard part of endonasal operations, the objective being to restrict mucosal bleeding during surgery. Adrenalin is used as a rule mixed with local anaesthetic, it is administered either topically on tampons or by injection infiltration of the mucosa. The use of adrenalin be associated with serious systemic complications. The authors describe two cases of young healthywomen whodeveloped ventricular fibrillation after infiltration of the mucosa with the anaesthetic containing adrenalin. The systemic effects of adrenalin are influenced by a number of factors - concentration and amount of administered adrenalin, the method of general anaesthesia, the general condition and associated diseases of the patient. During injection infiltration of the mucosa the systemic effects of adrenalin are more marked than during its surface application. For infiltration as a rule adrenalin solutions of a concentration 1:100 000 are recommended, for surface anaesthesia and vasoconstriction solutions with a concentration of 1:1000 - 1:20 000. Individual doses of adrenalin should not exceed 0.1 mg, the total dose 0.3 mg. Adrenalin should be used only incarefully monitored patientsandanaesthesia shouldbe sufficiently deep. From anaesthesia halothane should be eliminated which potentiates the arythmogenic action of adrenalin. Modern inhalation anaesthetics such as isofluran and sevofluran should have preference or else intravenous anaesthetics. The authors use for surface anaemisation in endonasal operations oxymethazoline (Nasivin), an adrenalin solutin 1:10 000, for infiltration of the mucosa an adrenalin solution 1:100 000. They have the preparations prepared in the pharmacy in bottles of 10 ml and the two solutions are for safety reasons differentiated by colour. Preparation of solutions of different concentrations by using drops of undiluted adrenalin into the anaesthetic in the operation theatre may be associated with errors and therefore the authors do not recommend it.

        Key words: adrenalin, concentration, systemic undesirable effects, general anaesthesia, risk of use.