Probiotics are proprietary formulations of specific microorganisms and quantified populations of live bacteria that are intended to confer a health benefit on the host. These different strains and combinations of microorganisms have a wide and varying range of clinical and immunologic capacities that can modify intestinal microbial populations in ways that can benefit the host. The enhanced presence of probiotic bacteria in the intestinal microbiota has been found to correlate with protection against atopy. The prevalence of allergic diseases such as asthma, allergic rhinitis, and atopic dermatitis has increased sharply over the past 2-3 decades in many countries, and allergies are now the most common chronic disease among children throughout the world. In the past few years, probiotics have been advocated for the management of allergic diseases in many parts of the world. So far, probiotics have shown more promise, albeit limited, in the primary prevention of allergic disease rather than in the treatment of established disease.