A correlation between the structure and lipophilicity has been carried out within the homologous members of two series of aliphatic bis(amides) and lipoamino acid conjugates of the anticancer drug methotrexate. Basing on their reversed-phase HPLC behaviour, the values of the experimental parameter RQ, obtained by using different mobile phases with increasing concentration of acetonitrile, were considered as a parameter of lipophilicity of the tested compounds. A comparison with their calculated log P was also performed.