Brain metastases occur in 20% to 40% of all patients with cancer, with an incidence 10 times higher than that of primary malignant brain tumours. The reported median survival of patients with brain metastases is only 1-2 months with corticosteroids and 5-7 months with whole brain radiotherapy (WBRT). But with improvements in neuroimaging, brain metastases are being diagnosed more frequently and with a lower burden of disease, such that approximately 50-60% of patients have 1 to 4 brain metastases at diagnosis. In these patients, stereotactic radiosurgery (SRS), a single high dose of radiation delivered with high precision to the target lesion, is being used increasingly as an alternative to surgical resection or as an adjunct to WBRT. The addition of SRS to WBRT has provided improvements in local control and functional autonomy for patients with oligometastatic brain disease, supporting the hypothesis that SRS increases efficacy against tumours resistant to the significantly lower doses used in WBRT.