A series of 2'-deoxynucleoside 5'-triphosphates (dNTPs) and their alpha-P-thio or alpha-P-borano analogues, i.e., (Sp-dNTPalphaS), (Rp-dNTPalphaB) and (Sp-dNTPalphaB) were studied as substrates for DNA dependent DNA polymerases and HIV-1 reverse transcriptase (RT). For HIV-1 RT the Rp-dNTPalphaB isomers are 1.2-fold better substrates than natural dNTPs. For DNA polymerases their efficiencies of incorporation are 3-fold (Klenow, Sequenase) and 5-fold (Taq) lower than for dNTPs. Thus, introduction of the alpha-boranophosphate group into dNTPs increases their selectivity to HIV-1 RT relative to bacterial DNA polymerases.