We previously showed that interferon (IFN)-gamma inhibited the proliferation of rat vascular smooth muscle cells (VSMC) by generation of nitric oxide (NO) through the induction of an NO synthase (NOS) and cloned the rat inducible NOS cDNA in VSMC (VSM-NOS). To study the regulation of human inducible NOS (hiNOS) transcription in VSMC, we now cloned and sequenced a 2.9-kb fragment for the hiNOS gene containing a putative promoter, exon 1 and exon 2. The 5'-flanking region contains several consensus sequences for the binding of transcription factors involved in the inducibility of other genes by cytokines. These include IFN-gamma responsive element and NF-IL6 and NF-kappa B binding consensus sequences. Interestingly, hiNOS gene contains a shear-stress responsive element (GAGACC) which was also found to exist in human endothelial-type NOS but not in murine inducible NOS.