We studied the effects of different diets at molecular, biochemical and cellular levels on rat mammary gland (MG). We looked at the potential protective outcome of those diets under exposure to Cadmiun (Cd), which is an important environmental contaminant. For this purpose, 4 female lots Wistar rats were used: 2 lots received casein and 2 lots soybean (Soy) as protein source. Within each group, 1 lot received regular water (control) and the other, 15 ppm of Cd in the drinking water for 60 days (6 animal in each experimental condition, 3 independent experiments).