This paper presents the basic tenets of the pre-Islamic criminal law that existed in the territory of present-day Iran. The basic principles of the law were derived directly from the state religion of Zoroastrianism and, most importantly, applied to all inhabitants of the area regardless of their religion. As a result, a significant part of the prohibitions and orders referred to moral issues characteristic of the state religion, such as rules for dealing with human corpses or acts of apostasy. The fall of the Sasanid dynasty and the adoption of Islam as the state religion brought an end to most of the legal institutions that referred to Zoroastrianism. However, the impact of these solutions on the Shariah-based legal system is still disputed in academia today.