A series of 2-iminopiperidines fused to small-membered rings (Tables 1 and 2) were synthesised and biologically evaluated using an in vitro human nitricoxidesynthase (NOS) inhibition assay. Fused bicyclic compounds 5-9 exhibited nearly the same potency as compound 1 in the hiNOS inhibition assay. Among these, the 1-methyl analogues 8 and 9 showed better isoform selectivity than their corresponding