Breakdown of the extracellular matrix leading to loss of articular cartilage and bone is a characteristic feature of arthritis. The author of this Review discusses the potential role of two novel members of the ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs) family, ADAMT-7 and ADAMTS-12, in the degradation of cartilage oligomeric matrix protein, and suggests that that α2-macroglobulin and granulin-epithelin precursor could represent their endogenous inhibitors.