Islam allows the marriage of more than one partner, provided that the husband can be fair and get permission from the first wife. As a result of polygamous marriages, there is legal uncertainty about joint assets, both in the first, second, third and fourth wives. The purpose of this paper is to find out the legal certainty of shared assets in polygamous marriages. The method used is a normative legal research method, using a regulatory approach, both Islamic law, Law Number 1 of 1974 and KHI. As a result, there is legal uncertainty especially for the first wife based on the Compilation of Islamic Law, specifically legal protection for the property with the wife brought in by her husband’s second marriage. According to Law No. 1 of 1974, each wife gets a second share, whereas according to Islamic law the status of a woman’s property does not change with the marriage. Keywords: polygamy, shared assets