Thirty random samples of UHT-milk were collected from different super markets in Assiut City, as well as lot was taken from factory at the time of manufacture and stored at room and refrigerator temperatures for up to 11 weeks and examined for their microbiological quality. The obtained results revealed that the average counts of aerobic plate, enter ococci, coliforms, B.cereus, psychrotrophic, thermophilic and thermoduric bacteria in supermarkets samples were 44x10, 50, 62.2, 13.8x10, 17x10, 73.3 and 70/ml respectively. Furthermore, E.coli, Klebsiella species, Entero bacter spp., citrobacter spp., Micrococcus spp., Staph. epidermidis and Anaerobic - spore formers could be isolated from the examined samples. Also the effect of storage temperature on the quality of UHT-milk was studied. The public health and economic significance of these findings are discussed.