Hydrogen sulphide (H₂S) is increasingly being recognized as an important signalling molecule in the cardiovascular and nervous systems. The production of H₂S from L-cysteine is catalysed primarily by two enzymes, cystathionine γ-lyase and cystathionine β-synthase. Evidence is accumulating to demonstrate that inhibitors of H₂S production or therapeutic H₂S donor compounds exert significant effects in various animal models of inflammation, reperfusion injury and circulatory shock. H₂S can also induce a reversible state of hypothermia and suspended-animation-like state in rodents. This article overviews the physiology and biochemistry of H₂S, summarizes the effects of H₂S inhibitors or H₂S donors in animal models of disease and outlines the potential options for the therapeutic exploitation of H₂S.