The crime of forgery in today’s criminal law is one of the most dangerous and common crimes that is most often committed by white-collar criminals. Apart from causing personal harm, committing this type of crime disrupts public comfort and welfare on a wide scale and may be a prelude or means to committing many other important crimes. In Iranian law, the legislator has avoided defining forgery and has only mentioned its examples, but in American law, the Model Penal Code, in Article 224-1, has comprehensively defined the above crime and stated its elements and conditions. In general, in Iranian and American law, the crime of forgery means making or changing a writing or document contrary to the truth and with the intention of fraud, but in Iranian law, forgery is considered a crime against public peace and interests, and in American law, it is considered a crime against property. In the following article, while examining the legal articles and with a comparative approach between the two legal systems of Iran and the United States of America, the similarities and differences in the field of the constituent elements of the crime of forgery, the advantages and disadvantages of these two systems in relation to the described crime are examined. A comparative study of the two systems can provide the basis for using the experiences of other countries and further research in the field of domestic law. However, it seems that despite similarities in the field of legislation, in some cases such as the conditions for the commission of the crime, malicious intent, type of punishment, etc., these two systems differ. Also, given the lack of a specific approach regarding the psychological element of the crime of forgery in Iranian legal doctrine and judicial practice, some judicial opinions in this regard areevaluated.