: Contemporary Issues Facing the Criminalization of Polygamy. According to ushûl al-fiqh, any act that disadvantages others is considered sinful. This is based on the principle that avoiding causing such disadvantages (mafsadât) is considered better than seeking advantages for oneself. Therefore, on the grounds that polygamy causes more disadvantages to wives and or children that it does advantages to those people, it can be categorised as a sinful act. In the fiqh context, polygamy is a jarîmah ta'zîr crime. But this is undermined by a lack of consensus about whether polygamy should be criminalised at all. Meanwhile, in the context of positive law in Indonesia, while the practice of polygamy is restricted the criminal sanctions for violating these restrictions are not clear. This article argues that polygamy is criminal both in terms of fiqh and positive law' However, in order for it to be properly stamped out, positive law needs to ensure that there are clear sanctions in place that directly correspond to acts of polygamy, such that the practice can be effectively criminalized.