Abstract: This experiment was conducted to study the surface activity of Whey Protein Concentrates (WPC). The Surface Tension (ST) of whey protein concentrates at various levels of ultrafiltration (1-4X) and at different protein loads (0.5, 1 and 2% w/v) were determined. Statistical analysis shows that there is no significant difference in the ST at 1 and 1.5X. However, at higher levels of ultrafiltration (2 up to 4X) the ST decrease with the protein load, except for WPC (3X) at 2% (w/v). At lower protein loads the ST decrease we observed a decrease in the ST while at higher protein loads the trend was different. The Interfacial Tensions (IT) reveal a different behaviour: the protein concentration does not significantly affect the surface tension except for WPC (1.5X) at 2% (w/v). Only at 2% w/v, the WPC IT was significantly affected. The surface free energy was not affected at protein loads varying between 0.5 and 1% for WPC concentrated to two times (X2). However, at 2%, we observed an increase in the (SE) except for WPC (X3). At a higher WPC (X4), the surface free energy increased with the protein load.