The genus Bifidobacterium consists of Gram-positive, immobile anaerobes with a variety of rod morphologies. It is one of the most common genera in the human gastrointestinal tract especially in newboms. At present, the genus Bifidobacterium includes 36 species, from which 13 were isolated from: faecal samples, orał cavity, vagina and human milk. The contribution of these bacteria to good health has been recognized many times. Their role is still under investigation and numerous studies have been carried out to investigate possible probiotic effect of these bacteria. The aim of this PhD thesis was to create a big collection composed of different species of bifidobacteria, to study the special properties of these strains, such as: antagonistic properties, surface properties, ability to adhere to human enterocyte-like cell lines, called Caco-2 and HT- 29, resistance to bile salts and to selected antibiotics, and to analyze their usefulness as probiotics. As a result of this research, a detailed description of the strains collected was produced and a few Bifidobacterium strains have been chosen as good candidates for probiotics, but more research, especially clinical, should be done.