The right of access to a lawyer is a human right and a criterion for guaranteeing the right to a fair trial.The recognition of this right and its limitations differ in the legal systems studied.The question of the article is:What is the right of access to a lawyer in international criminal law and Iranian criminal law?What are the similarities and differences between them?And the answer to it is through an analytical and comparative method and strategies for guaranteeing that right.The findings of the article indicate differences in the patterns of recognition,guarantee,and order of limitation of that right despite the similarities and commonalities between them.Despite the recognition of the above right in the aforementioned legal systems, the aforementioned right is limited in the ordinary laws of Iranian criminal law.The legal and procedural limitation of the aforementioned right in this system,unlike international criminal law,despite its relative similarities in recognizing the right of access to a lawyer,has fundamental legal and procedural differences with the human rights norms contained in international criminal law,which indicates a difference in the pattern of recognition and the order of inclusion and limitation of that right.Recognition and guaranteeing the right of access to a chosen lawyer is the basis of a fair trial, and its limitation causes a violation and injustice of the criminal trial,which requires examining the model of limiting the right of access to a lawyer and moving towards a model of guaranteeing access to it in order to achieve justice in criminal proceedings and its fairness