Arbitration in the Works of PROFESSOR Jafari Langroudi The works of Dr. Mohammad Jaafar Jafari Langroudi are considered as a precious literary, jurisprudential and legal collection. In this article, among the various legal institutions that were considered by him, we shall analyze the topic of “ arbitration” in his works. The first section of the article is devoted to the substantive rules of arbitration, in which elements of arbitration are discussed. In one of his works, he explains and interprets elements of arbitration, including the parties involved, the granting of mediation authority to the arbitrator and prohibition of mediation in criminal affairs and retribution. A brief history of arbitration is also mentioned in the first section of the article. In one of his books, the PROFESSOR describes the position and history of mediation in Islam, the conduct of the Infallible Imams and the Rightly-Guided Caliphs, and the time and manner of the advent of the institution of arbitration in Iran. Then, part of this section continues with a comparison of arbitration with the institution of the bar. In the same section safeguards for non-compliance with the conditions for validity of the contract or the condition of arbitration are set forth. Arbitration by a legal entity which is discussed in the category of the substantive rules of arbitration, is considered justified in the works of Dr Langroudi. With respect to the validity of the arbitrator’ s award, in case there are several arbitrators, the PROFESSOR also considers valid the opinion of the majority, and considers the arbitration null and void in case there are two arbitrators and they fail to agree. The second section of the article deals with procedural rules in the arbitration domain. In another section of the article, the PROFESSOR’ s works have been analyzed concerning objection to arbitration award and the procedure to file an application to set aside the award in question. In respect to termination of arbitration, Dr. langroudi believes that it is possible to withdraw from arbitration by resorting to certain evidence and circumstances.