The gene coding for human collagenase-3 (CLG3), a recently described matrix metalloproteinase produced by breast carcinomas, has been localized by fluorescence in situ hybridization on chromosome 11q22.3. Physical mapping of an isolated YAC clone containing CLG3 has revealed that this gene is tightly linked to those encoding other matrix metalloproteinases, including fibroblast collagenase (CLG1), stromelysin-1 (STMY1), and stromelysin-2 (STMY2). Further mapping of this region using pulsed-field gel electrophoresis has shown that the CLG3 gene is localized to the telomeric side of the matrix metalloproteinase cluster, the relative order of the loci being centromere-STMY2-CLG1-STMY1-CLG3-telomere.