A new series of 1-(1,3-benzodioxol-5-ylmethyl)-3-[4-(1H-Imidazol-1-yl)phenoxy]-piperidine analogs were designed and identified as potent and selective inhibitors of NO formation based both on the crystal structure of a murine iNOS Delta 114 monomer domain/ inhibitor complex and inhibition of the NO formation in human A172 cell assays. Compound 12S showed high potency and high iNOS selectivity versus nNOS and eNOS. (C) 2007 Elsevier Ltd. All rights reserved.