This study was carried out to investigate the changes of sensory, microbiological and chemical quality by storage conditions in ultra-high temperature (UHT) treated milk for 6 months from August 2000 to February 2001. A total of 1,340 UHT pasteurized milk samples collected from 3 plants (A, B and C) were stored at 10℃ and room temperature (dark and light exposure) for 6 months. The bacterial counts in the milk samples stored at 10℃ were kept less than standard limit (2×104 cfu/ml) of bacteria for 5 days, and bacterial counts in some milk samples were a slightly increased more than the standard limit as time elapsed for 6 months. When the milk samples were stored at room (3℃∼30℃), the bacterial counts in most of the milk samples from A plant were more than the standard limit after 3 days of storage, but in the 20%∼30% (4∼6/20) of the milk samples from B and C were less than the standard limit after 6 months of storage. The sensory quality and acidity of milk were gradually changed in proportion to bacterial counts during storage at room temperature and 10℃ for 6 months. The standard limit of bacteria in whole market milk was more sensitive than those of sensory and chemical test as standards to determine the unaccepted milk. No significant correlation was found in keeping quality of the UHT milk between dark and light exposure at room for 6 months. The compositions of fat, solids not fat, protein and lactose in milk samples were not significantly changed according to the storage conditions and time for 6 months. The UHT sterilized milk samples (A plant; 20 samples, B plant; 110 samples) collected from 2 plants were not changed sensory, chemical and microbiological quality by storage conditions for 6 months, but only one sample from B was detected the bacteria after 60 days of storage. The shelf life of UHT pasteurized milk in this study was a little longer than that reported by previous surveys. Although the shelf life of UHT pasteurized milk made a significant difference among three milk plants, the results indicated that some UHT pasteurized milk in polyethylene coated carton pack could be stored at room temperature for 6 months.