One of the key questions in the studies of the Roman cult of Mithras has been, since the works of F. Cumont, the question about the religious historical origin of the cult – regarding which there is no consensus to this day. Theories about the origin of the cult can be divided into three groups: (1) the so-called “strong” Iranian thesis, according to which the cult was imported from Iran; (2) the so-called “weak” Iranian thesis, claiming that just a few, mostly irrelevant elements of the cult originated in Iran; (3) a radical stance that there is no consistency between the Roman cult of Mithras and the Iranian cult of Mithra and what the two have in common is simply the similar name of a god. The author of this presentation has studied comparatively the character of Mitra in Indian religious literature, that of Mithra in Iranian religious and mythological texts as well as in Iranian religious iconography, and Mithras in the cult devoted to him in Rome, and has concluded that the radical belief common in current Mithras studies, according to which Mithras is connected with Mitra and Mithra only by them having similar names, is just as erroneous as the “strong” Iranian thesis defended by F. Cumont and G. Widengren. Although it is certain that the Roman cult of Mithras is not a cult imported from Iran, but a new cult that originated in the Roman Empire, the author of this presentation maintains that the Roman cult of Mithras contains a series of motifs that can be found both in the Vedas and in Iranian mythological texts: connection of Mitra/Mithras with friendship and a contract of friendship; certain military traits; connection with cosmogony and the cosmic order; connection with light, the Sun and the chariot of Sol; the role of the god as a giver of water and fertility; the idea of a sacrifice that stimulates fertility. Based on the sources linked to the Roman Mithras, in particular the iconography, it may be claimed that a large part of these motifs did not have a peripheral role in the mythology connected with the cult, but they carried an important, maybe even a central role. As the previously mentioned motifs were already interrelated in India and Iran, the author of this presentation believes that their coexistence in the mythology of the Roman cult of Mithras cannot be a coincidence but testifies to the wider Indo-Iranian background of the central figure of the cult, the god Mithras, which should not be ignored even if the Roman cult of Mithras is viewed as a new cult that evolved in the Roman Empire and within the context of the Greco-Roman religion.