An emerging topic attracting the attention of various sciences such as medicine, psychology, sociology, jurisprudence, and law is gender change. Currently, some people do not accept gender change issue and react to it. Instead, some consider it as a cure for disease and have a rational view. Many contemporary jurists allow gender change, but they have not explained its legal consequences, especially in couples' relationships. This research uses descriptive and analytical method and reliable jurisprudential and legal sources, and examines the reasons for gender change legitimacy and its effects on the family’s legal system. If the gender is changed based on valid medical standards and experts' approval, some aspects of rights will be affected. If a right is derived from a contract, the origin of the right should be determined by the former gender’s role. If gender played an essential role in it, then with the change of gender, the said contract is invalid and as a result, the rights arising from it are also canceled accordingly. But if the change of gender had a secondary role in it, the contract remains despite the change of gender and is conditional. If there is a legitimate rational interest in the existence and continuation of the former sex, the contract can be terminated. The non-contractual rights of the mentioned person may also be an acquired right that gender change will not affect these rights. In addition, this person can enjoy other rights according to the new gender.