The mature fruits of three species of algarroba found in Bolivia (Prosopis chilensis (Molina) Stunz, P. alba Grisebach y P. nigra (Grisebach) Hieronymus) and of one of Brazil (P. juliflora (SW) DC) were analysed for some nutritional and antinutritional factors. P. nigra showed the highest levels of crude protein (11.33 g/100 g dry matter-DM) and ashes (4.12 g/100 g DM). P. juliflora presented the lowest levels of lipids (0.79 g/100 g DM), crude protein (8.84 g/100 g DM) and dietary fiber (40.15 g/100 g DM), and the highest levels of non reducing sugar (52.51 g/100 g DM) and in vitro protein digestibility (66.45%). Trypsin inhibitors concentration (0.29 to 9.32 UTI/mg DM) was inferior to that of raw soy; P. juliflora presented the higher values. Regarding saponin, hemagglutinin and poliphenol values, the levels found are considered low. As for nitrates, the levels found were higher than those reported for peas and beans, with P. chilensis presenting the highest value (2.92 g NO3(-)/kg DM). The levels of phytate varied from 1.31 a 1.53 g/100 g.