The synthesis of a new family of D4T analogues is described to study the influence of pyrazinone base on antiretroviral power. Substitution of 3H by methyl or n-decyl increases the lipophilic character and may facilitate diffusion across cell membranes. The compounds were characterized by H-1 NMR and infrared spectroscopy. Antiviral (HIV-1) properties of these compounds were examined.