This study was planned to investigate the effect of aditional lyzozyme to milk on growth performances of Holstein calves. About 15 female and 18 male Holstein calves were used in this study. Between day 4 and 60, calves were fed with whole milk from a pail twice a day such that each calf received 228 L whole milk (4 L day(-1)) over the whole experiment All calves were fed ad libitum with calf starter along with alfalfa hay. Calves was fed with milk which is additional (10 mg L-1) lysozyme during milk fed period. During 0-35 days period of the experiment, lysozyme supplementation decreased daily gain and increased feed to gain ratio (p<0.05) and male calve had higher daily gain, feed intake and better feed to gain ratio in. the same period (p<0.01). The effects of lysozyme and gender on daily gain. and feed to gain ratio have disappeared during 35-60 days period. Lysozyme decreased feed intake (p<0.05) during 35-60 days of experiment. Similarly overall feed intake, daily gain and feed to gain ratio were not affected by lysozyme (p>0.05). Male calve had higher daily gain and weaning weight and lower feed to gain ratio than female calve throughout the study (p<0.05). Lysozyme x gender interaction affected feed intake in all experimental period and male receiving control diet had higher feed intake than female but lysozyme supplemented male calves had lower feed intake than female ones (p<0.05). The results revealed that lysozyme may deteriorate of adaptation of the microflora of the gastrointestinal system of 5 weeks old calves and be tended to decrease diarrhea cases during preweaning period.