This study examined the survival and acid stress response of nine lactic acid bacteria (LAB) including Lactobacillus rhamnosus strain GG in commercially available yoghurt products (low pH environment) during the long-term storage. Under the storage conditions investigated (52 weeks period at 5 °C), there was a loss of the viability of Lactobacillus acidophilus, Lactobacillus casei and Bifidobacterium sp. within 35 weeks. However, L. rhamnosus strain GG, one of starter strains in a commercially available yoghurt product, exhibited excellent survival throughout the whole storage period. Our results indicate that the viability of L. rhamnosus strain GG was increased by modulating the stress-related factors as well as the activity of ATPase with exposure to the low pH conditions.