Background & objectives: Since the incidence of vancomycin- and methicillin-resistant Gram- positive infections continue to increase, novel antimicrobials such as linezolid and streptogramin may provide new options to treat patients. The aim of this study was to investigate in vitro susceptibility of Enterococcus faecium resistant to glycopeptides, coagulase negative staphylococci and S. aureus resistant to methicillin isolated mainly from blood and also rectal swab cultures of patients against quinupristin/dalfopristin and linezolid. Methods: The in vitro susceptibility to linezolid and quinupristin/dalfopristin for a total of 332 isolates of Gram-positive cocci [127 methicillin-resistant Staphylococcus aureus, 109 methicillin- resistant coagulase negative staphylococci (71 S. epidermidis, 38 S. haemolyticus) and 96 vanA genotype vancomycin-resistant Enterococcus faecium] was investigated by E test. Results: All MRSA and MRCoNS isolates were susceptible to linezolid (MICs < 4.0 mg/l). Ninety per cent of VRE isolates were inhibited by linezolid at concentration of 2.0 mg/l and presented similar activities to quinupristin/dalfopristin. MICs for quinupristin/dalfopristin against staphylococci were also low (MIC 90 = 1.0 mg/l for both MRSA and MRCoNS isolates). Interpretation & conclusion: The results of the present study demonstrated that quinupristin/ dalfopristin and linezolid, have good in vitro activity against MRSA, MRCoNS and vancomycin resistant E. faecium in Turkey. These drugs could be promising therapeutic options in an era of rapidly growing antibiotic resistance in all parts of world. The incidence of infections caused by multidrug resistant (MDR) Gram-positive bacteria is increasing despite the advances in antibacterial therapy over the last few years. The most problematic pathogens include strains of enterococci resistant to Indian J Med Res 120, December 2004, pp 546-552 Key words Enterococci-linezolid-methicillin resistance-quinupristin/dalfopristin-staphylococci-vancomycin resistance 546 In vitro activity of linezolid & quinupristin/dalfopristin against Gram-positive cocci Alper Tünger*, Söhret Aydemir, Servet Uluer & Feriha Cilli Department of Microbiology and Clinical Microbiology, Ege University Medical Faculty, Izmir, Turkey Received December 30, 2003 ¸ glycopeptides, and staphylococci resistant to methicillin. These organisms are frequently resistant to the other most currently available antibacterials, and the infections are extremely difficult to treat. Thus, new antibiotics are required to treat infections caused by these MDR organisms 1,2 .