A new streptogramin antibiotic XRP 2868 was compared with quinupristin-dalfopristin for inhibitory activities against antibiotic-resistant Haemophilus influenzae, Staphylococcus aureus, and Streptococcus pneumoniae. In each organism examined, XRP 2868 had an IC50 that was twofold to fivefold lower than quinupristin-dalfopristin, for inhibition of cell viability, protein synthesis, and ribosomal subunit formation.