Potential matrix-associated elements in the 5'-region of the rat estrogen sulfotransferase gene (Ste1) were searched for and characterized. The DNA fragments corresponding to the regions -800/+1048 and +1049/+2038 relative to the main point of transcription initiation were found to be bound to the nuclear matrix in vitro. A permanent association of the 5'-region of the Ste1 gene with the nuclear matrix in rat hepatocytes was found, the most probable site of attachment being the region -352/-152. No differences were found in the attachment of the 5'-region of the Ste1 gene to the nuclear matrix in the liver of males where the gene is actively transcribed and in that of females where it is inactive.