A total of 96 bulk milk samples from buffaloe's and Friesian cow's were examined throughout eight months lactation period, in Upper and lower Egypt to evaluate suita bility of such milk for preparation of ultra high temperatue products. The evalua tion of heat stability of milk was done using two well known methods (Oil-bath and ethanol tests) measuring the stability of raw milk to high temperature. The relia bility of both methods was also mentioned. Heat stability of buffaloe's and cow's milk varied at different months of lactation period but reach maximum stability in the mid-lactation. Cow's milk in Lower Egypt is characterized by distinctly poor heat stability at the beginning and the end of lactation if compared with buffaloe's milk. Statistically analysing the data of the two methods measuring heat stability of milk showed highly significant coefficient correlation. Recommendations for acceptance of raw milk, to ensure successful processing of sterile milk and milk powder were also given.