Due to dietary proteins exert many functionalities by means of biologically active peptides which are inactive within their parent proteins. So out target was to separate these biological active peptides from their parent proteins using a simple cheap method for fractionation like ammonium sulfate precipitation after enzymatic hydrolysis. Egg is a natural food which provides numerous nutritional and biologically active substances. Egg white is the richest natural source of proteins. In our study we make hydrolysis for hen egg white lysozyme using peptic digestion then the hydrolysates were separated by ammonium sulfate precipitation and determine the antibacterial activity of the separated peptides against different bacterial strains comparing with native lysozyme using liquid broth with studying the molecular structure by using electrophoresis. Our results declared that, the fraction 2% was the most potent antibacterial activity then followed by LzP3. On the other hand, fraction 4% was similar in the antibacterial activity with native lysozyme. Electrophoresis showed similar molecular structure between fraction 4% and native lysozyme and between LzP3 and fraction 4% but with high intensity for the low molecular weight peptides which was responsible for the potent antibacterial activity. On conclusion, low molecular weight peptides produced from lysozyme hydrolysates with strong antibacterial activity can be applied for food biopreservation or for therapeutic uses in the future.