The aim of this work was to use ultrafiltration (UF) to isolate lysozyme directly from chicken egg white. It was concluded that the specific activity of lysozyme, degree of its purification and enzyme recovery depended significantly on the dilution of egg white solution, its pH and ionic strength. A significant rise in lysozyme activity and efficiency of the enzyme separation was observed after the isolation was carried out with the use of membranes with increasing cut-off. Under the best separation conditions the enzyme activity was 12.400 U/mg, coefficient of purification degree (the ratio of enzyme specific activity in the preparation, to the initial enzyme activity in raw material before isolation) received level 17 and the recovery of lysozyme was about 20%.