Abstract: Alternative splicing can result in up to four forms of human tyrosine hydroxylase (HTH) mRNA (mRNAHTH). In the adrenal gland, a major site of catecholamine biosynthesis, the presence of all four mRNAHTH forms is controversial. In the present study, postmortem human adrenal medullary tissue was analyzed for the presence of multiple forms of HTH protein by blot immunolabeling. Electrophoretic transfers were developed with affinity-purified rabbit anti-HTH antibodies raised against peptides that reproduced the unique amino acid sequences predicted by the four mRNAHTH forms. All four of the predicted HTH protein forms were present in the adrenal glands from a diverse sample population.