We cloned and sequenced the mouse phenylethanolamine N-methyltransferase (PNMT) gene which encodes the enzyme that catalyses the conversion of norepinephrine to epinephrine. The ability of various length sequences flanking the mouse or human PNMT genes to direct expression of reporter genes in transgenic mice was examined. We show that 9 kb of 5' flanking sequences from the cloned mouse PNMT gene can direct expression of the Escherichia coli beta-galactosidase (lacZ) gene to predicted regions of the adrenal, eye and brain in the adult transgenic mouse. The transgene was also expressed during development, in the myelencephalon, adrenal medulla and dorsal root ganglia. PNMT-producing cells were ablated by expression of the diphtheria toxin (DT-A) gene driven by the human PNMT promoter, resulting in abnormalities in the adrenal medulla, eye and testis. The hPNMT8 kb-DT-A line presents a model with which to examine the developmental ramifications of deletion of PNMT-producing cell populations from the adrenal medulla and retina.