objective: to ratify the effect of traditional "nixtamalización" upon aflatoxin in corn, to identify the residual compound in dough, to evaluate its toxicity, and to verify the effect of acidic treatment on the regeneration of aflatoxin. material and methods: corn with and without aflatoxin was treated separately with lime and heat to obtain two types of dough. aflatoxin and the residual compound were quantified by high pressure liquid chromatography (hplc) and toxicity was evaluated in eight day old chicks. results: "nixtamalización" destroyed afb1 (96%) and aflatoxicol (70%). the residual compound was identified as afb1. experimental animals died by ingestion of 260 mg of afb1 dough containing residual aflatoxin was not toxic. acidic. treatment did not increase aflatoxin concentration, nor aflatoxicol. conclusions: the results support the use of traditional "nixtamalización" as a means to inactivate aflatoxin in corn and that acidic treatment prevents its regeneration in dough.