The article analyzes two cases of borrowing Zoroastrian mythological motifs by Syriac-speaking Christians during the period of Late Antiquity. The first example, attested in the writings of Ephrem the Syrian (4th c.), concerns the case of reinterpretation of the traditional image of biblical Paradise as a cosmic mountain, encircling the whole world. Most probably, it developed under a direct influence of the Iranian cosmological traditions regarding the mountain Alburz. The second example concerns the use of the figure of Rapitvin, known from Zoroastrian mythology, by the anonymous author of the Syriac composition known as the “Cave of Treasures” (6th–7th cc.). The discussed examples of appropriation of some elements of Zoroastrian mythology by Syriac-speaking authors provide us with a valuable evidence on the complicated and multifaceted process of acculturation of the Christian minority to the culture of Sasanian Iran.