Thyroid hormone receptors (TR) are ligand-dependent, DNA-binding, trans-acting transcriptional factors belonging to the erbA-related steroid/thyroid hormone receptor superfamily. To better understand the structural and functional characteristics of TRs, we isolated the gene encoding human TR beta 1 (hTR beta 1). The coding region of hTR beta 1 is split into at least eight exons. Each exon well correlates with functional domains of hTR beta 1 protein, and the exon/intron organization is highly conserved when compared with the chicken c-erbA gene which encodes an alpha-type chicken TR. We demonstrate that hTR beta has at least two mRNA forms having different lengths of the 3'untranslated region. We also note several nucleotide corrections of hTR beta 1 cDNA sequence.