This thesis research was conducted to measure true digestibility and the gastrointestinal endogenous losses of copper, iron, manganese, selenium, and zinc in corn soybean meal-based diets with a commercial vitamin-trace mineral premix at 4 gradient levels through the linear regression of the apparent digestible vs. the total dietary intake of the concerned trace minerals in the weanling pigs. The dietary treatments did not affect (P > 0.05) growth performances, the digestive functions, and gastrointestinal responses in the pigs during the 11-day study. With the regression analyses, true total tract micro-mineral digestibility and endogenous losses associated with the assay diets and the premix were respectively determined. In conclusion, total tract endogenous losses represent significant components of the micro-mineral requirements and homeostasis; and true digestible micro-mineral supply should be considered in swine diet formulations to reduce feeding costs and the detrimental impacts of excessive swine manure trace minerals on the environment.