Aflatoxins represent one of the biggest public health problems in food safety, due to their toxic potential for humans and animals. They can lead to serious threats, such as hepatotoxicity, teratogenicity and immunotoxicity. Maize is the most important cereal consumed in Mexico, with which tortillas, tamales, flours, toasts and other products are elaborated. The elaboration of tortillas begins with nixtamalisation, which is an ancient maize process, developed and applied by indigenous Mesoamerican population. Some studies have shown the effect of nixtamalisation in the inactivation of aflatoxins. The purpose of this research was to record the traditional nixtamalisation process (TNP) and to register the presence of the aflatoxin B₁ (AFB₁) in tortillas and the exposure to AFB₁ in indigenous communities living in the Huasteca Potosina, in central México. To register the nixtamalisation technique, a questionnaire was given to women, to illustrate the process step by step. Digestion, extraction, purification, and identification of the adduct AFB₁-lysine (AFB₁-Lys) in serum were performed. The TNP was analysed by 51 surveys, 4% of the tortillas was above the maximum permissible levels, according to Mexican guidelines; however, all blood samples showed presence of AFB₁. TNP done in indigenous communities in the Huasteca Potosina region is not efficient enough to eliminate aflatoxins present in contaminated maize. It is necessary to improve conditions of places in which the grain is stored and knowledge about the risk of exposure to aflatoxins in rural communities, as key steps for preventing exposure to this type of mycotoxins.