The gradual increase of degenerative diseases observed in the last decades has been raising morbidity, incapacitation and mortality. The occurrence of these kinds of diseases is related to the aging of humanity as well as the unhealthy choices of individuals, particularly those dwelling in large urban centers, which are closely linked with poor nutrition, obesity, and tobacco and alcohol consumption. The introduction of functional compounds in the diet seems to be an attractive alternative to ameliorate the quality of life of all age groups. The prebiotics stand out because of their beneficial effects, favoring the growth of colonic microbiota, helping the gastrointestinal metabolism, and regulating the serum cholesterol and mineral absorption. Experimental data indicates that prebiotics could reduce the severity or incidence of degenerative diseases, such as neoplasias, diabetics, coronary diseases, and infectious diseases. They also seem to promote a positive modulation of the immune system. Their effects on the immune system could even be associated to increase of resistance to infection and microbicide capability, as well as to a decrease in allergic reactions. This article's goal is to analyze the immunomodulatory potential of prebiotics observed in experimental and trial studies. © 2011 Elsevier Ltd.