A study was conducted to evaluate the new VITEK 2 system (bioMérieux) for identification and antibiotic susceptibility testing of gram-positive cocci. Clinical isolates of Staphylococcus aureus (n ‫؍‬ 100), coagulasenegative staphylococci (CNS) (n ‫؍‬ 100), Enterococcus spp. (n ‫؍‬ 89), Streptococcus agalactiae (n ‫؍‬ 29), and Streptococcus pneumoniae (n ‫؍‬ 66) were examined with the ID-GPC identification card and with the AST-P515 (for staphylococci), AST-P516 (for enterococci and S. agalactiae) and AST-P506 (for pneumococci) susceptibility cards. The identification comparison methods were the API Staph for staphylococci and the API 20 Strep for streptococci and enterococci; for antimicrobial susceptibility testing, the agar dilution method according to the procedure of the National Committee for Clinical Laboratory Standards (NCCLS) was used. The VITEK 2 system correctly identified to the species level (only one choice or after simple supplementary tests) 99% of S. aureus, 96.5% of S. agalactiae, 96.9% of S. pneumoniae, 92.7% of Enterococcus faecalis, 91.3% of Staphylococcus haemolyticus, and 88% of Staphylococcus epidermidis but was least able to identify Enterococcus faecium (71.4% correct). More than 90% of gram-positive cocci were identified within 3 h. According to the NCCLS breakpoints, antimicrobial susceptibility testing with the VITEK 2 system gave 96% correct category agreement, 0.82% very major errors, 0.17% major errors, and 2.7% minor errors. Antimicrobial susceptibility testing showed category agreement from 94 to 100% for S. aureus, from 90 to 100% for CNS, from 91 to 100% for enterococci, from 96 to 100% for S. agalactiae, and from 91 to 100% for S. pneumoniae. Microorganism-antibiotic combinations that gave very major errors were CNS-erythromycin, CNS-oxacillin, enterococci-teicoplanin, and enterococci-high-concentration gentamicin. Major errors were observed for CNS-oxacillin and S. agalactiaetetracycline combinations. In conclusion the results of this study indicate that the VITEK 2 system represents an accurate and acceptable means for performing identification and antibiotic susceptibility tests with medically relevant gram-positive cocci.Automation in clinical microbiology is still in a very early stage of development compared with the level of automation that has been achieved in clinical chemistry, hematology, and immunology laboratories.In the last 20 years, a variety of automated systems for the identification and antimicrobial susceptibility testing (AST) of microorganisms has been developed based on automated interpretation of the results of biochemical tests or using microdilution trays following overnight incubation and photometric determination of growth (6,18,20,21). Advances in technology that may provide rapid bacterial identification and AST are now recognized as having both clinical and financial benefits (2).The VITEK system originated in the 1970s as an automated system for identification and AST and has evolved today into the VITEK 2 system, which automatically performs ...