In this study, scrutinizing the nature and basis of civil liability of physicians revealed that although jurist shave not discussed and reviewed the notion of loss of opportunity to improve or cure the patient explicitly, this is clearly inferred from their utterance about the concept of damage and their prediction about common criteria for measuring the damage. Considering that now a days, the custom of society considers such opportunities as worthy, thus, losing them is considered as a kind of damage, so, according to Islam, in such cases, the physicians who cause the loss of opportunity to improve or cure their patients will be responsible. And this responsibility is different from the ultimate responsibility- i.e. death, disability, exacerbation of disease & etc-, in nature. This theory is widely applicable in medical law in some Islamic countries, common law legal system and especially in French law and many sentences have been issued based on it, so that it is one of the controversial issues of civil liability in causation & being obvious damage. In Iran law this theory is seemed to be executable in civil liability of physicians, regardless of whether it is missed opportunities or creating undue & already occurred risk, however, it is not opposite to the general principles of legal and religious precepts.