Essential to the administration of justice, the lawyer plays a key role in postulating a decision favorable to his constituent and convincing the judge. However, it is common in nature to the formation and performance of bad professionals, who, due to their inconsistent actions or omissions, cause damage, whether material or moral, in the face of claims to be reached by their contractors, forming in the popular imagination a pejorative stereotype regarding the performance. from the lawyer. However, it is part of this area, a very small percentage that denigrate the image of valuable operators of the law. Thus, the Civil Liability of the Lawyer before the Theory of the Loss of a Chance becomes possible, because through misery, lack of knowledge, among others, according to the Brazilian Bar Association, lead the professional services contractor. attorneys to suffer direct or indirect damages, as they see the possibility of obtaining any economic advantage or avoid an injury, given the lost chance. Thus, even if the damage is uncertain, but if concrete probabilities are present, it should be compensated, not for the unwanted end result, but for the mere loss of the chance of achieving it.