A human genomic DNA fragment in phage lambda containing FSHB, the gene for the beta-subunit of human follicle-stimulating hormone (FSH-beta), was analyzed and the nucleotide sequence of the region of the clone encoding FSH-beta was determined. A subclone of the lambda phage containing 67% of FSH-beta coding sequence was used as hybridization probe to determine the human chromosomal location of FSHB. A panel of mouse-human somatic cell hybrids containing reduced numbers of human chromosomes was screened with the FSHB probe; complete cosegregation of FSHB with human chromosome 11 was observed in all 26 cell hybrids tested. Analysis of a set of cell hybrids containing translocated derivatives of chromosome 11 further localized FSHB to the human chromosome region 11p11.2----11pter. A Hind III restriction fragment length polymorphism (RFLP) detected by another subclone of the lambda phage containing FSHB now provides a genetic marker for this region of the human genome.