This book discusses about the different dietary protein levels and its effect on performance of grower pigs. As dietary protein is the sole source of protein for the body since, protein derived from the feed is converted to body protein. Among all the nutrient present in the diet, dietary protein is a key nutrient that influences the digestibility and utilization of feeds, which in turn helps in the growth of the animal. An optimum protein level in the diet is very much necessary as different protein levels are required at different physiological stages. Efficient and profitable swine production depends upon an understanding of the concepts of genetics, environment, herd health, management and nutrition. These factors interacts each other and their net output determines the level of production and profitability. Since feed represents about 70-75 % of the total cost of pork production and protein is the most costly item in formulating swine ration. Excessive protein level in the feed does not only mean high formulation costs, but can also affect pigs performance. Thus a thorough knowledge of the swine nutrition is essential in order to maintain a profitable swine enterprise.