13-L-2',3'-Dideoxyadenosine, [3-L-2',3'-didehydro-2',3'-dideoxyadenosine and related compounds were synthesized in a stereoselective manner. These compounds were tested in vitro against HBV in 2.2.15 cell line and against HIV-1 in PBM and CEM cells. It was found that 13-L-2',3'-didehydro-2',3'-dideoxyadenosine (7) exhibited significant anti-HIV (ECso 0.38 taM in PBM cells) and anti-HBV activity (ECso 1.2 I.tM).