Fiber reinforced polymers (FRPs) due to their specific high-strength properties become more and more popular and replace traditional structural materials like conventional steel in prestressed concrete structures. FRP reinforced structures are relatively new when compared to structures prestressed with steel tendons. For that reason only several studies and applications of pre-tensioned FRP reinforcement have been conducted until now. Moreover, researchers only considered short-term behavior of FRP reinforced concrete members. The precise information about long-term behavior of FRP reinforcement is necessary to evaluate the prestress losses, which should be taken into account in the design of prestressed RC structures. One of the most important factor influencing long term behavior of FRP reinforcement is stress relaxation. The overview of experimental tests results described in the available literature considering the prestress losses obtained in FRP prestressed concrete members is presented herein.