A variety of factors influence intraocular pressure. An increase for example, can be found under conditions of hypoventilation, prohibited ventilation and too light anaesthesia. Some pressure decreasing factors are barbiturates, various inhalation anaesthetics, neuroleptics, and also hyperventilation. In 10 gynaecological patients with normal ophthalmological status, IOP was measured under enflurane anaesthesia by means of a Draeger hand-held applanation tonometer. The neuroleptanaesthesia served as a basis. After anaesthetic conditions were stabilized, concentrations of enflurane ranging from 0.5 to 2.0 vol.% were administered. Under constant ventilation (PECO2) the following parameters were measured: pH, PCO2cap,PO2cap,base excess, minute ventilation, respiratory rate, blood pressure and pulse rate. The concentration of enflurane was measured by gas-chromatography. The IOP was decreased by using enflurane in various concentrations. This decrease is caused by enflurane/itself and is independent of blood pressure changes.