Water-based drilling mud lubricants using a blend of fatty acid polyamine salts and fatty acid esters give synergistically better lubricity results than either component used separately. For example, the blends with different ratios of fatty acid diethylenetriamine salt and fatty acid methyl ester demonstrate much better lubricity in water-based drilling fluids than those where only fatty acid diethylenetriamine salt or fatty acid methyl ester are separately used. The amines in fatty acid amine salt might also include other polyamines, such as butanediamine pentamethylenediamine, spermidine, spermine, propylene diamine and propylene polyamines. The fatty acid esters might also include fatty acid ethyl ester, fatty acid glycerol ester and fatty acid trimethylolpropane ester. The carbon numbers of the fatty acids used to make the components in the lubricant blend may range from C4 to C28.