With the growing interest in self-care and integrative medicine coupled with our health-embracing increasing population, recognition of the link between diet and health has never been stronger. As a result, the market for functional foods, or foods that promote health beyond providing basic nutrition, is flourishing. Within the functional foods movement is the small but rapidly expanding arena of probiotics - live microbial food supplements that beneficially affect an individual by improving intestinal microbial balance. The consumers' overwhelming interest in and demand for functional foods, including probiotics, make it imperative that health professionals stay abreast of the latest research findings and available products. The global market for functional foods in the coming years is predicted to grow rapidly. Although Japan currently accounts for about one-half of this market, the fastest rate of growth is expected to be in the United States. Probiotic products represent a strong growth area within the functional foods group and intense research efforts are under way to develop dairy products into which probiotic organisms such as Lactobacillus and Bifidobacterium species are incorporated. Such probiotic foods may modulate gut microbial composition, thereby leading to improved gut health, for example, through improved tolerance to lactose in lactose-intolerant individuals or improved resistance to pathogenic bacteria. The fast-growing probiotics market holds a wealth of opportunities, especially for those companies that understand and cater for the final consumer. This monograph provides a summary of research on the health benefits of probiotics and offers information regarding the global market potential of probiotics.