The authors report a study of 60 years of French Jurisprudence in relation to the medical contract in cosmetic surgery. Although the obligation can only be in the form of means in the case of surgery of living tissues, a special obligation nevertheless applies when the operation is not performed as a therapeutic procedure but at the patient's wishes. It is an obligation of caution and diligence, respecting the role of proportionality in the indications and the means applied to obtain the desired objective and the safety of the patient. The application of these means will be judged by the magistrate more severely than in therapeutic surgery. A certain degree of laxity in the investigation of a causal relationship in civil law has led to the use of the concept of decreased chance of survival for the compensation of victims of serious complications occurring during cosmetic surgical operations.