The child's right to know their origins is a fundamental aspect of children's rights and is crucial for the development of everyone’s identity. The aim of this paper is to present the legal regulation of a child's origin in family law. The introductory part of the paper will explain the child's right to know their origins, which is regulated by the Family Law Act and the UN Convention on the Children’s Rights, laying the foundation for further analysis. The paper will define the legal mechanisms for establishing or disputing a child's origin from the father and mother. Special attention will be given to the right of a child conceived through medically assisted reproduction to know their origins, as well as the right of an adopted child, since these cases present specific challenges and ethical dilemmas. The discussion will address legal obstacles and practical issues that arise in these procedures, with a particular focus on the importance of protecting the child's interests. Finally, the significance of the role of the Croatian Institute for Social Work will be highlighted as one of the key institutions in legal proceedings concerning the protection of the child's right to know their origins. In conclusion, the paper emphasizes the need for further improvement of the legislative framework to ensure the full and effective respect of the child's right to know their origins, which is in their best interest.