A series of (5S) N-(3-{3-fluoro-4-[4-(3-aryl-4,5-dihydro-isoxazole-5-carbonyl)-piperazin-1-yl]-phenyl}-2-oxo-oxazolidin-5-ylmethyl)-acetamide(6a-o) were synthesized and their in vitro antibacterial activity against various resistant Gram-positive and Gram-negative bacteria were evaluated. Most of the synthesized compounds showed 2 to 10 fold lower MIC values compared to linezolid against Staphylococcus aureusATCC 25923, ATCC 70069, ATCC 29213,Bacillus cereusMTCC 430,Enterococcus faecalisMTCC439,Klebsiella pneumoniaeATCC 27736, and Streptococcus pyogens.