The aim of this research was to isolate Bifidobacterium spp. as probiotic strain from healthy infant stool. After that, study the role of this strain in lowering cholesterol level, enhancement of immunoglobulins ( IgG & IgM ) and effect of this strain on pathogenic bacteria in intestinal tract. The finally use this strain to produce functional dairy products. Twenty-three presumptive Bifidobacterium strains were isolated from healthy infant stools. On the basis of all of the identification tests twelve strains isolated from the stool were identified as B. breve, eight strains were identified as B. infants and three strains were identified as B. bifidum. B. breve (9/12 strains), B. infants (7/8 stains) and B.bifidum (2/3 strains) were tolerable to bile salt. However, B. breve (8/12 strains) and B. infants (5/8 strains) and B. bifidum (1/3 strains) were tolerant in pH 3.0. All strains are not able to grow at pH 1.0 or 2.0. Bifidobacterium breve  (No. 7) that is characterized by low pH stability, bile salt tolerance and has antimicrobial activity was selected from healthy infant stools to be used as probiotic in mice nutrition This strain has significant role in lowering cholesterol level, enhancement of IgG and has positive effect on decrease count of E. coli and Staph. aureus in  intestinal tract. On the other hand, the count of B .breve and organoleptic score of probiotic yogurt with this strain reached to high score during the storage period.