The aim of this paper is to present Parthian-Armenian relations from the end of the 2nd century BCE to the so-called Treaty of Rhandeia (63 CE). This covers the period from the first contact of both states to the final conclusion of long-drawn-out military conflicts over Armenia between the Arsacids ruling the Parthian Empire and Rome. The author discusses reasons for the Parthian involvement in Armenia during the rule of Mithradates II and various efforts of the Arsacids to win control over this area. He also identifies three phases of their politics towards Armenia in the discussed period.