Given the need to identify new materials that allow the replacement of the use of antibiotics in animal production systems, this study assessed the effects of the inclusion of dietary lysozyme on productive parameters and the intestinal villi morphology in red tilapia (Oreochromis sp) during the stage of masculinization. 0, 350, 700 g/ton of dietary lysozyme and androgenic hormone 17 Alpha-methyltestosterone (60 mg/kg) during 30 days, 900 post larvae (mean 0.003 g weight) were fed. Every 7 days were measure size, weight and calculate production parameters evaluated. To measure the mucosa of the foregut 3 sampled from each treatment at the end of the experimental period. The evaluation of productive parameters showed no significant differences in fish fed with different levels of lysozyme inclusion. The growth of the intestinal mucosa at level of 350 g/ton of lysozyme was statistically different. With this it is shown that the inclusion of lysozyme in tilapia diets, positively affects the growth of the same.