In this article, we outline the current state of knowledge about the balance between collagen production and degradation in idiopathic pulmonary fibrosis (IPF). The dysregulated action of metalloproteinases implicated in IPF may play a central role in IPF pathogenesis. Inhibiting metalloproteinases in IPF may, therefore, have therapeutic potential, but our knowledge of their pathophysiological role is held back by limited animal models and the lack of specific inhibitors.