The purpose of this study was to elaborate bread with yacon flour at two different levels (6% and 11%) and to analyze their proximate composition, their glycemic indices and their prebiotic potentials in vitro. Bread with 6% and 11% of yacon flour presented, simultaneously, low and moderate glycemic index. As for the prebiotic potentials, it was evident the presence of probiotic bacteria, particularly Lactobacillus. The results showed that, the addition of yacon flour on bread rendered products from low to moderate GI, with prebiotic potential, low fat and high fiber contents, according to the Brazilian food legislation.