An efficient method for the synthesis of N(9)-[3-fluoro-2-(phosphonomethoxy)propyl] (FPMP) derivatives of purine bases has been developed. Both (R)- and (S)-enantiomers of the N(6)-substituted FPMP derivatives of adenine and 2,6-diaminopurine were prepared and their anti-human immunodeficiency virus (HIV) and anti-Moloney murine sarcoma virus (MSV) activity was evaluated. Whereas none of the 6-substituted FPMPA derivatives showed any antiviral activity, several FPMPDAP derivatives had a moderate antiretroviral activity. Moreover, the data obtained from the study of the substrate activity of the active derivatives towards N(6)-methyl-AMP aminohydrolase support the notion that the studied N(6)-substituted FPMPDAP derivatives act as prodrugs of the antiretroviral FPMPG analogues.