Stereotactic Ablative Radiotherapy (SABR) was first developed at the Karolinska Institute in the 1990s. Using the principles of cranial radiosurgery, i.e. multiple radiation beams all focused on the tumour and a custom made body frame to immobilize the patient they were able to safely deliver high "ablative" radiotherapy doses. Other centres in North America, Japan and Europe then developed lung SABR for stage I NSCLC and lung metastases, defining which tumours to treat and what dose was required. This was coupled with revolution in radiotherapy technology with improved methods for tumour definition radiotherapy planning and image-guided radiotherapy.Now, for peripheral stage I NSCLC local control rates of >95% are achievable with minimal acute toxicity (even for patients with very poor lung function) and lung SABR is now an accepted as a standard treated for medically inoperable suitable stage I NSCLC patients. However for central tumours, i.e. close to the major airways, heart and oesophagus, there is still much debate on what radiation dose is safe and this is currently being investigated by the RTOG in North America and a proposed EORTC study. In the UK the UK SABR consortium was created in 2007 to address the lack of SABR. The consortium is a multi-disciplinary group involving clinicians, medical physicists and radiographers that wrote national guidelines for lung SABR. Since these guidelines were agreed in 2009 more than 10 centres offer lung SABR in the UK with a further 10 expected in 2013.Research is a key focus for the consortium with many trials in development including a RCT of SABR versus surgery in patients with peripheral Stage I NSCLC considered at higher risk of resection.Therefore in the future, SABR may be a less invasive yet as effective alternative to surgery for curable stage I NSCLC.