beta-L-2',3'-Dideoxyadenosine, beta-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 beta-L-2',3'-didehydro-2',3'-dideoxyadenosine (7) exhibited significant anti-HIV (EC(50) 0.38 mu M in PBM cells) and anti-HBV activity (EC(50) 1.2 mu M). Copyright (C) 1996 Elsevier Science Ltd