This study examined the impact of shiitake mushroom extract (ME) on the viability and / enzyme activity of Bifidobacterium breve ATCC 15701 and Lactobacillus reuteri DSM20016 in yoghurt during refrigerated storage. The presence of ME significantly enhanced the viability of both strains. L.reuteri DSM20016 exhibited better stability in yoghurt than B.breve ATCC 15701. L.reuteri DSM20016 showed the highest viability in yoghurt samples containing 4% ME, followed by B.breve ATCC 15701, and then control samples. Results suggest that ME can be used as a natural additive to dairy products to improve the growth and viability of L.reuteri DSM20016 and B.breve ATCC 15701 strains.