Fraud is one of the vices of voluntary acts, together with the error, force or intimidation, simulation and fraud.Definition: " malicious towards the implementation of an act is any assertion of what is false or disguise of the true, any artifice, cunning or machination which is used for that purpose " ( conf. Article 931 Argentine Civil Code ) 2Requisitos:son four requirements that fraud can determine the cancellation of the event: has been severe: that is suitable to mislead a person that puts ordinary care in handling their affairs. If it were so rude to a minimum precaution it had been exposed, the mens rea is not serious.Determinant of the action of the subject to whom vitiates the will have been causes: means such deception without which the Act does not had been conducted.That has caused significant damage: that is of economic significance for the person who suffers.There have been no reciprocal-malice: justice cannot be to discuss the traps that employ the unscrupulous.