SUMMARY
The current article deals with comparative study of the nature and the effects of conflict among national courts and authorities of international arbitrations using descriptive analytical method. In this research, the conflict between the jurisdiction and the rules of national courts and authorities of international arbitrations has been studied by having a glance at the law in Iran and other countries by using valid internal and external resources and the contents of the conventions of international arbitrations.The results of the study suggest that if there is a valid arbitration agreement, the courts do not have the jurisdiction to deal with the issue. Therefore, the effect of arbitration agreement is that the jurisdiction of state courts for dealing with the issue is excluded. The conflict of jurisdiction occurs if it is brought up simultaneously in an international court of arbitration and a state court .this kind of conflict can theoretically be the result of two different theories : (A) A theory which believes that the government has been delegated to administer the justice before being known as the legislator ,(B) a theory which believes that choosing the judge of yourself is the natural human rights and so this kind of right should be protected against any interference and violation by the legislator .These two theories have been replaced by another theory which is a combination of them and by the replaced theory ,they have had a peaceful coexistence . According to the second theory , it is true that the government can administer justice,however it does not mean that in all conditions, it can administer the justice all by itself by its courts. If the government keeps the ability of controlling the administration of justice by other organizations such as the courts of arbitration ,then the justice is served .