Novel 6-phenylselenenyl-5-propyluracils were synthesized from 5-propyluracil with the use of regioselective synthesis to give 1-[(2-hydroxyethoxy)-methyl]-6-phenylselenenyl-5-propyluracil (6), 1-ethoxymethyl-6-phenylselenenyl-5-propyluracil (9) and 1-benzyloxymethyl-6-phenylselenenyl-5-propyluracil (10). Interaction of these compounds with recombinant HIV-1 reverse transcriptase (RT) was evaluated using a non-isotopic colorimetric method. Compounds 9 and 10 exerted potent HIV RT inhibition (IC(50) 0.06 and 0.05 microM respectively) while compound 6 showed moderate inhibition (IC(50) = 3.5 microM). Potent anti-HIV-1 activity in MT-2 cells inoculated by a syncythia-inducing HIV-1 (cat #3 strain) laboratory isolate was exerted by compounds 9 and 10 (EC(50) 0.62 microM and 0.025 microM, respectively), while compound 6 showed only moderate activity (IC(50) = 4.1 microM). In addition, compound 10 showed very good in vitro therapeutic index (TI > 2046), indicating that it is a potential anti-HIV/AIDS drug.