New ethyl 3,4-dihydro-3-oxo-4,6,7-trisubstituted-2H-1,4-benzoxazine-2-acetate derivatives were synthesized and their structures were elucidated by IR, H-1 NMR and mass spectral data. Antimicrobial activity of the compounds was investigated by using the method of twofold serial dilution technique against different Gram-positive, Gram-negative bacteria and some Candida species in comparison to standard drugs. Microbiological results indicated that the synthesized compounds possessed a broad spectrum of activity having MIC values of 6.25-100 mu g/ml against the tested microorganisms. The QSAR analysis of a set of these compounds tested for growth inhibitory activity against Candida krusei was performed by using the computer-assisted multiple regression procedure. The activity contributions for substituent effects of these compounds were determined from the correlation equation for predictions of the lead optimization. (c) 2006 Elsevier Masson SAS. All rights reserved.