The aim of the present work was to study the effect of heat treatments and seasons of year on immunoglobulin, lactoferrin and lysozyme contents in camel's, cow's and buffalo's milk. The milk samples were heat treated at 63, 72, and 95°C for 30 min., 15 sec. and 15 min. respectively. Camel's milk contained significantly higher amounts of immunoglobulin (IG), lactoferrin (LF) and lysozyme (LZ) than cow's and buffalo's milk. Heating milk at 63°C /30 min. had significant effect on lysozyme and lactoferrin. While the immunoglobulin was more affected in the three kinds of milk. The amounts of immunoglobulin of cow's and buffalo's milk were observed at 72°C /15 sec. compared with camel's immunoglobulin. The amounts of lactoferrin were lost at 95°C /15 min. in all kinds of milk. However, at this level of heat treatment, the losses of lysozyme at 95°C /15 min. were 0.12 ± 0.18, 0.06 ± 0.17 and 0.02 ± 0.14 ug/ml for camel's, cow's and buffalo's milk, respectively. When milk was heated at 95°C /15 min. camel's milk protective proteins were relatively more heat resistant than cow's and buffalo's milk proteins. It was found that the heat resistance for lysozyme > lactoferrin > immunoglobulin. The amounts of milk protective proteins were higher in winter for all kinds of milk, compared with summer milk.