Perkawinan dianggap sah apabila dilakukan menurut agama dan juga hukum yang berlaku. Untuk mendapatkan bukti yang sah secara hukum, perkawinan wajib dicatatkan di Kantor Urusan Agama atau Kantor Catatan Sipil. Perkawinan yang tidak dicatatkan mengakibatkan kedudukan hukum yang lemah bagi istri dan anak. Salah satunya adalah Hak Mewaris. Dalam Putusan Pengadilan Putusan Mahkamah Agung No 1482 K/Pdt/2013, istri pertama secara tiba-tiba menuntut hak waris untuk anak dan dirinya ketika pewaris meninggal dunia. Istri sah dari perkawinan ke tiga pewaris merasa keberatan, karena istri pertama tersebut telah meninggalkan pewaris selama ± 17 tahun. Perkawinan pewaris dan istri pertama tidak dicatatakan di Kantor Catatan Sipil. Istri sah pewaris menggugat agar istri pertama dan anaknya tidak mendapatkan hak waris. Penelitian dilakukan secara normatif, dalam penelitian ini data yang digunakan adalah data sekunder dengan pendekatan hukum dan pendekatan kasus. Dari hasil penelitian tersebut, dapat disimpulkan bahwa pada putusan Putusan Mahkamah Agung No 1482 K/Pdt/2013 tersebut yang berhak mewaris ialah istri pertama yang pernikahannya tidak dicatatkan di Kantor Catatan Sipil dan anak dari hasil perkawinan tersebut. / Marriage is considered legal if it is done according to religion and also the applicable law. To obtain legal proof, a marriage must be registered at the Office of Religious Affairs or the Civil Registry Office. Unregistered marriages result in a weak legal position for his wife and children. One of which is inheritance rights. In the Decision of the Supreme Court No 1482 K/Pdt/2013, the first wife suddenly demanded inheritance rights for her child and herself when the heir died. Legitimate wife of marriage to three heirs objected, because the first wife had left the heir for ± 17 years. The marriage of the heir and his first wife were not registered at the Civil Registry Office. The legal wife of the testator sues for the first wife and child not to get inheritance rights. The study was conducted normatively, in this study the data used were secondary data with a legal approach and a case approach. From the results of these studies, it can be concluded that the Supreme Court Decision No 1482K/Pdt/2013 those who are entitled to inherit are the first wife whose marriage is not registered at the Civil Registry Office and the child from the marriage.