Rent is a bilateral contract and as such the other contracts, the considerations on both parts must be determined at the time that the contract is concluded. According to the general principles of contracts, if a consideration is indeterminate, the contract will be void. However, under article 3 of the landlord and tenant acts, 1977 and 1983, non-determination of leasehold in a verbal lease contract will not render the contract void and if there is difference between the parties, the court will determine the leasehold. This rule is an exception to the general principles and determination of leasehold by the court ignores the autonomy of the parties in tenant contract. In this article, the authors first examine the matter of non-determination of leasehold in the Jurisprudence and then they will describe the subject under Iranian laws.