This paper treats the relationship between vengeance and witchcraft in the contemporary Guaraní-speaking indigenous region of Isoso, in the Bolivian Chaco. The cases study discussed are about accusations of witchcraft that have generated a retaliation action of vengeance. The argument is that the vengeance is a language that expresses a moral idea, turning into a norm a violent behaviour if validated and substantiated by an idea of justice. Indeed, vengeance is corrects only if it is exercised as a violent retaliatory action against witchcraft. The article concludes that the vengeance in Isoso continues to be conceived as a violent reciprocity mechanism even if the homicide now is forbidden. This because the vengeance still remains a thought model that establishes the community legal imagination and represents the conflictive relationship with witchcraft.