We present the sequence of 2770 nucleotides of 5' flanking sequence of the human estrogen receptor (hER) gene. The positions of potential binding sites for a number of trans-acting factors including Sp1, OTF-1, INR, TATA and CAAT box factors as well as several half palindromic hormone responsive elements (HREs) have been mapped by comparison with the consensus binding sequences. A long alternating purine/pyrimidine (APP) tract which has the potential for structural diversity as indicated by site-specific cleavage with S1 nuclease is another feature of this region. The organization of this promoter region is compared to that of other cloned members of this family. The potential roles that these sequences may play in the transcriptional regulation of this gene are discussed.