A positional scanning library of N-alkylglycine trimers (peptoids) containing over 10 000 compounds has been synthesized on solid phase. The synthetic pathway involved the use of the submonomer strategy and a set of 22 commercially available primary amines as a chemical diversity source. The unbiased nature of the library allowed its screening against a variety of biological targets, leading to the identification of individual peptoids exhibiting remarkable biological activities (García-Martínez, C. et al. Proc. Natl. Acad. Sci. U.S.A. 2002, 99, 2374. Montoliu, et al. J. Pharm. Exp. Therap. 2002, 302, 29. Planells-Cases, R., et al. J. Pharm. Exp. Therap. 2002, 302, 163). In the present work, the screening of this library against a panel of Gram-positive and Gram-negative bacteria led to the identification of different compounds exhibiting antimicrobial activity.