Hydrogen sulfide is believed to be a signalling molecule in the central nervous system. It is known to increase rapidly following an ischemic insult in experimental stroke. Is it protective or deleterious? This review surveys the relevant information available in the literature. It appears that there is no definitive answer to this question at present. Current evidence seems to suggest that the presence of H2S in the ischemic brain may either be deleterious or protective depending on its concentration, deleterious when high and protective when low. Therefore, it can be inferred that either an enhancement or a reduction of its concentration may be of potential use in future stroke therapy.