The in vitro inhibitory and bactericidal activity of echinomycin and its the novel synthetic analogues of echinomycin YK2000 and YK2005, were evaluated using 93 clinical isolates of vancomycin-resistant enterococci (VRE). In agar dilution tests, the MIC90 of echinomycin and YK2000 were 0.125 and 8mg/l, respectively, using Mueller-Hinton 11 agar, while that of YK2005 was 32mg/l. Bactericidal activity of echinomycin and YK2000 were two to four times higher than the MIC in time-kill assay experiments. These results suggest that echinomycin and its analogues might be useful as anti-VRE drugs. (C) 2004 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.