A highly purified recombinant glycoprotein form of human THYROID-STIMULATING HORMONE, produced by recombinant DNA technology comprising two non-covalently linked subunits, an alpha subunit of 92 amino acid residues containing two N-linked glycosylation sites, and a beta subunit of 118 residues containing one N-linked glycosylation site. The amino acid sequence of thyrotropin alfa is identical to that of human pituitary thyroid stimulating hormone.