Pristinamycin displays unique antibacterial properties due to the synergy between its two components, pristinamycin I and pristinamycin II. Because this antibiotic is not water-soluble, its administration is restricted to the oral route, and its therapeutic potential is thereby limited. Novel water-soluble derivatives of the naturally-occurring antibiotic pristinamycin were obtained by modifications of its two major components. The modifications included regioselective and stereoselective substitution a to the carbonyl group in the 4-oxo-pipecolic acid residue of pristinamycin I A (PIA) and stereoselective conjugate addition to the double bond of the dehydroproline ring in pristinamycin II A (PII A ). We report here the in-vitro and in-vivo activities of some representative water-soluble derivatives of pristinamycin I A and pristinamycin II A against Staphylococcus aureus reference strains, sensitive or resistant to methicillin and/or macrolides.