Chromatographic RMwand log k'wparameters have been used as alternatives to the shake flask n-octanol/water partition coefficient method to study the lipophilic character of several known pyrimidinic nucleoside derivatives and two novel ones. The RMand log k' values were measured by means of reversed-phase thin-layer chromatography (RP-TLC) and reversed-phase high performance liquid chromatography (RP-HPLC) respectively. Good linear relationships were observed between log P values obtained from the classical shake flask method (log Po/w) and each one of those obtained by chromatographic techniques (log PRP-TLCand log PRP-HPLC) and by theoretical calculations using the CLOGP program (log PCLOGP). The RMwand log k'wvalues have proven to be reliable parameters for describing the lipophilic properties of this family of compounds.