Option of condition in endowment Abstract Endowment is a permanent legal act and after the endowments created, the Endower cannot destroy the Endowment and refer to the endowment property. Many of the Imamiyyah jurists and lawyers of the country have emphasized on the permanence of the endowment and its irrevocability. Despite the emphasis that endowment is a permanent legal act, the examination of jurisprudential works shows that some jurists have foreseen the possibility of including option clause in endowment in certain cases. Most of the jurists have accepted such conditions and various evidences have been presented to prove the validity of such conditions. The civil law has not accepted this point of view and it can be deduced from its various articles that the validity and irrevocability of the endowment are the inherent characteristics of this contract and under no circumstances can a condition be made in the endowment that the cause of the endowment returns to the owner of the benefactor. Therefore, What is mentioned as the condition of termination or revocation in some jurisprudential works is basically outside the establishment of endowment. Key words: endowment, detention, Emphasis on the permanence of the endowment, option of condition, property release