Since the early years of the Sasanian Empire, the effigy of each Sasanian king was placed on the obverse of the coins, and on the reverse side there was an atashdan altar, depicting where a sacred fire burned. Its image demonstrated the importance of Zoroastrianism as a state religion. A commitment to preserving a certain number of altar components – there were seven altogether – speaks of the sacred purpose of the object and the existence of the canons that were followed during its construction. The article analyzes compositions of atashdans mainly according to the images known from publications of Sasanian coins and copies of coins of the Sasanian mint. The author notes the gradual schematization of atashdan iconography from monumentality to decorativeness, linking this phenomenon with a weakening of the role of the Zoroastrian religion in the life of the state and society.