Using a cDNA probe, two genomic clones were obtained encoding the human tissue inhibitor of metalloproteinases-3 (TIMP-3). Analysis of these clones showed that they contained four distal exons and three introns of the gene. Although the intron-exon structure is similar to that of the timp1 gene, the first intron of the timp3 gene is much longer, being at least 17.5 kb in size.