The collagenases of the matrix metalloproteinase family are key enzymes in mediating irreversible cartilage collagen loss in arthritis. Inhibition of these enzymes is, therefore, an important therapeutic target. New approaches to collagenase inhibition include active site inhibitors designed for specific enzymes, inhibition of cell signalling molecules and transcription factors involved in collagenase gene expression, prevention of zymogen activation and induction of natural inhibitor production.