The transfer of lawsuits, as one of the less-explored institutions in Iranian procedural law and registration law, refers to a situation in which the beneficiary of a lawsuit transfers their position in the proceedings or prior to them to another person. Although this concept appears similar to the transfer of a right, it fundamentally differs in terms of its nature, effects, and formal requirements, especially in connection with official documents and the provisions of the Deeds and Real Estate Registration Law. The registration law, by emphasizing the role of official registration and its effects on third parties, directly impacts the possibility, validity, and consequences of transferring lawsuits related to registered properties. The aim of this study is to clarify the concept of lawsuit transfer and examine its status within the Iranian legal system, focusing on selected provisions of the Deeds and Real Estate Registration Law, while analyzing its legal and practical effects in the judicial process. The main research question is: What role do the provisions of the registration law play in the transferability of lawsuits and their effects on the parties and the course of proceedings? The research methodology is descriptive–analytical, utilizing library research, analysis of statutory provisions, and review of judicial precedents. The findings indicate that although the registration law does not directly address the transfer of lawsuits, the requirements regarding official registration particularly in disputes concerning immovable property play a decisive role in the validity and consequences of such transfers, and neglecting these requirements may result in procedural conflicts and prolongation of proceedings. Ultimately, the study concludes that a more precise clarification of the status of lawsuit transfer and harmonization of procedural regulations with the registration law is an undeniable necessity to ensure legal security and coherence in judicial practice.