Growing public awareness of diet-related health issues has fuelled the demand for probiotic foods, which are currently restricted predominantly to fermented milk drinks and yogurt. Probiotics are bacteria, generally lactobacilli or bifidobacteria associated with a plethora of health benefits ranging from alleviation of symptoms of lactose intolerance, treatment of diarrhoea, cancer suppression to reduction of blood cholesterol (Naidu et. al. 1999 for review). While cheese has long been associated with a high quality nutritional image, more recently, research efforts devoted to the development of probiotic cheese containing viable numbers of Lactobacillus and Bifidobacterium sp. With demonstrated health promoting properties, have been made to push cheese into the 'functional foods' category. Generally, incorporation of probiotic bacteria into milk-based food systems, including cheese provides challenges in terms of maintaining viability and probiotic functionality during manufacture and shelf-line. In contrast to yogurt and fermented milk products, many hard cheeses such as cheddar have long ripening times of up to two years. During the time, the added probiotic bacteria would need to grow and/or survive to sufficient numbers to deliver the probiotic effect in the gastrointestinal tract. Since cultures can vary considerably with regard to their performance in cheese and intestinal environments, strain selection is vital to the successful development of probiotic cheese, as is retention of probiotic activity in the ripened product. Nevertheless, studies have demonstrated that cheddar cheese is suitable as a potential probiotic 'functional food' for a number of bifidobacteria and lactobacilli, with demonstrated health benefits. Our studies and others have led to the development of various probiotic cheeses, containing strains of probiotic bifidobacteria, lactobacilli and enterococci. Indeed, we have demonstrated that cheese can be an excellent carrier of some health-promoting bacteria, and that it also has certain advantages over yogurt and fermented milk as a delivery system for some probiotic strains.