The aim of the study was to evaluate selected quality factors, such as: sensory value, L(+)lactic acid content, titratable acidity and survival rate of 10 Bifidobacterium strains, during 21 days’ storage, in nonfermented and fermented bifidus milk. The results of the studies show that good quality of bifidus milk can be maintained only in cold storage. All the studied strains produce nearly nothing but L(+) lactic acid. After 21 days the percentage of this acid in the total amount of lactic acid exceeds 90%, independently of storage conditions.