The purpose of this dissertation is to declare the position of the bank in case of receiving documents in violation of the terms mentioned in the letter of credit According to Omani law, and that by answering the following questions: 1 - What is the legal nature of the obligation of the bank (opening credit) to the beneficiary (the seller)? 2 - What are the stages of the opening credit? What are its functions? What are the main advantages ? 3 - What are the types of documentary credits in the Omani law? 4 - What are the criteria for conformity of the documents? 5 - What are the effects of matching documents with the terms of credit or non-conformity in the acceptance of documents or non acceptance? 6 - What are the impacts of presenting documents during the period of validity of accreditation? 7- What are the legal effects of presenting the documents after the end of the period of validity of Documentary credit ? 8- What proposals can be developed if the submission of documents in violation of the accreditation required? 9- What are the responsibilities of banks in documentary credit? The above questions were answered based on the analysis, and comparison between the Uniform custom and practice [ UCP ] No.600 of 2007 issued by the International Chamber of Commerce [ICC], and the provisions of the Trade Act No. 55/1999CE Oman. The main results of this dissertation are : 1 - The transfer of the documentary instructions as required between the two parties should be accurate in order to avoid the disputes that might arise due to the violation of one of the two parties as the instructions required to avoid conflicts, 2 - The Omani law regulated all matters of documentary credit in ten articles only , while in Uniform custom and practice