The genomic sequence of human interleukin-11 (IL11) has been isolated based on its sequence homology with a cDNA clone encoding primate IL11. The human IL11 genomic sequence is 7 kb in length and consists of five exons and four introns. The IL11 gene has been localized to the long arm of human chromosome 19 at band 19q13.3-q13.4 by in situ hybridization. Several potential transcriptional control sequences that may play an important role in the control of IL11 gene expression have been identified within the 5'-flanking region of the human IL11 gene. The 5'-flanking region of the human IL11 gene contains sequences similar to those present in the 5'-regulatory regions of other cytokine genes. Four repeats of a 30-bp DNA segment were found in the fourth intron, and several copies of ATTTA and Alu repetitive sequences were identified in the 3'-noncoding region of the human IL11 gene. A DNA sequence (ACATGGCAAAACCC) that has 71% similarity with the IL1-responsive element of the IL6 gene was found in the 3'-flanking region of the human IL11 gene. The two polyadenylation sites located at nucleotide positions 6762 and 5591 correspond to the 2.5- and 1.5-kb IL11 transcripts expressed in IL1-induced PU-34 cells. The availability of the human IL11 genomic sequence should aid in studies of the regulatory mechanisms of IL11 gene expression in different cell types and the role of IL11 expression in the hematopoietic microenvironment.