R-L-ddC (5), R-L-ddA (6), R-L-d4T (7) and R-L-d4C (8) (enantiomers of natural dideoxynucleoside analogues with known potent HIV activity) were prepared as potential anti-HIV agents. 2',3'-Dideoxynucleosides analogues have been extensively studied as potential anti-HIV agents [1]. These analogues exert their antiviral effect by being converted to their corresponding triphosphates; these triphosphates then act as inhibitors of the unique viral enzyme reverse transcriptase (RT) [2-4]. While several structural analogues, with both sugar and base modifications, have been prepared as potential anti-HIV agents [5], little work has been done on the enantiomers of known anti-HIV agents [6]. We now report on the preparation and biological activities of compounds 5-12, geometric isomers of four known (1-4) HIV agents. C = cytosine, T = thymine, A = adenine