Prosopis alba and Prosopis chilensis, popularly called carob trees in the South American Chaco, are arboreal species. Carob fruits are an ancestral food for human consumption, mainly in the form of flour. In recent years, the study of carob trees in Paraguay has been based on the development of silvo-pastoral systems for livestock or as animal feed; very little is known about the compositional characteristics of the different varieties of carob that are part of the food systems, and that are used for the production of flours. Samples of flour from three autochthonous varieties of carob trees from the Central Chaco are evaluated for human consumption as a potential food ingredient in processed foods. They are evaluated for nutritional contribution, antioxidant potential and the preliminary evaluation of safety at the microbiological level. Official AOAC methods were used. The carob flour samples presented low humidity (less than 6%) and water activity (less than 0.45). The flours of the three species analyzed presented significant differences in their content of carbohydrates, lipids, proteins, dietary fiber and, consequently, in their caloric value, with a high content of polyphenols and antioxidant potential detected by ABTS. Presence of mesophilic aerobes, total coliforms and yeasts in the samples was observed. These results demonstrate the great food potential of carob flour from the Paraguayan Chaco, and indicate the need to address the food safety aspects of this type of wild-harvested food, to enhance their added value as ingredients for foodstuffs in the diet of regional populations.