Although in most legal systems and even in Islamic countries whose codes are drawn from Sunni jurisprudence, the nature of medical obligations is the obligation to means, but in some special cases and according justifiable reasons in accordance with the requirements and the new order ruling the society and regarding to a simultaneous attention to the order and justice, the nature of medical obligations is the obligation to results. Apparently in the Iranian's legal system following the majority of Emamyeh's jurisprudence, the nature of medical obligations has been introduced as the obligation to results which seems be able to criticized.

However the acceptance of this subject -obligation to results of the obligation of the surgeons in unnecessary cosmetic surgeries - seems reasonable, logical and consistent with the realities of the society. So in this article, with a brief description of the history of the subject and the views of proponents and opponents, the nature of medical obligations and their examples it's been tried to comparatively study. An analytical investigation of the nature of the obligations of the surgeons has been dealt with in some controversial, common and related instances, i.e cosmetic surgery- either necessary or unnecessary-.