The Rev Response Element (RRE) forms an oligomeric complex with the viral protein Rev to facilitate the nuclear export of intron-retaining viral RNAs during the late phase of HIV-1 infection. However, our structural understanding of this crucial virological process remains limited. In this study, we determined several crystal structures of an intact RRE stem-loop II in two distinct conformations, performed negative-staining electron microscopy and molecular dynamics simulations, and revealed that this three-way junction RNA exhibits remarkable structural plasticity. Through