BMP-3b (also termed GDF-10) is a novel BMP-3 related protein recently discovered in rat femur tissue by molecular cloning. In this paper, we have isolated cDNA and the gene for human BMP-3b and determined their structure. Cloned human BMP-3b cDNA with a size of 2632 base pairs encodes a 478 amino acid precursor protein sharing 83% identity with rat BMP-3b. The human BMP-3b gene is composed of 3 exons and spans approximately 13 kilobases of DNA. The 5′-flanking region carries no typical TATA box but G+C rich sequences. Southern blot analysis revealed that the BMP-3b gene is situated in a single locus of chromosome 10. By Northern analysis, human BMP-3b transcripts were detected primarily in femur, brain, lung, skeletal muscle, pancreas and testis.