Surgery has traditionally been regarded as the treatment of choice for patients with stage I non-small cell lung cancer. However, the morbidity and mortality associated with surgery in elderly patients with considerable comorbidity remains of concern, as are the poor 5-year survival rates. Until recently, conventional radiation therapy was the only alternative curative treatment option for patients who were unfit for surgery, but with lower local control rates that were inferior to those with surgery. However, a growing body of clinical data on outcomes with newer nonsurgical treatment options such as stereotactic radiation therapy (SRT) and radiofrequency ablation (RFA) is now available. SRT is a noninvasive method showing a 2-year local control rate in excess of 85% in both T1 and T2 tumors after three to eight fractions of high-precision radiotherapy. Despite the use of very high radiation doses, high-grade toxicity is limited to approximately 5% of patients. Percutaneous RFA is an invasive method showing 2-year local control rates of approximately 64% in smaller tumors, but results are poorer in lesions > or =3 cm. Compared with SRT, a higher procedure-related morbidity and mortality rate has been reported, mainly caused by pneumothorax and hemorrhage. Although data from randomized trials of conventional radiotherapy versus SRT or RFA are not available, the use of SRT is becoming widespread for patients who are unfit for surgery. Reported 2-year local control rates after SRT are comparable with those achieved with surgery, and prospective randomized trials comparing surgery with SRT in patients who are fit to undergo surgery are now being planned.