Zintevir is a DNA 17mer that forms a quadruplex and shows strong anti-human immunodeficiency virus (HIV)-1 activity. The quadruplex formation is thought to be essential for the anti-HIV-1 activity of Zintevir. We synthesized the enantiomer of Zintevir and evaluated its structure and anti-HIV-1 activity. The results showed that the enantiomer has anti-HIV-1 activity comparable to that of Zintevir although it forms the mirror image quadruplex structure of Zintevir.