In patients who suffer a subarachnoid haemorrhage, the greatest risk of mortality and morbidity is in those who go on to develop delayed cerebral vasospasm. There are currently no British guidelines for prevention and management of this complication, with treatment varying between centres. This review aims to evaluate the current progress in prevention and treatment research, including novel therapies. Most good quality clinical trials have focused on prevention, supporting the use of triple H therapy and calcium channel blockers for prophylaxis. There is also some evidence for other medications, for example tirilazad and magnesium, although further research may be needed to demonstrate any benefit over and above that achieved with other more commonly used preventive measures. Less research is available on treatments to reverse vasospasm once it has begun, although at present balloon angioplasty and calcium channel blockers seem to remain the best supported, enabling some reversal of constriction. However, as this is a complex pathophysiological process, there are many potential targets for therapy, and as our understanding of this improves, novel therapies which can improve the outlook for these patients are likely to be developed.