Advances in technology have changed the treatment of patients with early stage non-small-cell lung cancer who are not healthy enough for standard surgical resection. Previously, patients with severe underlying cardiopulmonary dysfunction were often dissuaded from pursuing definitive therapy, even though most patients died from their lung cancer and not as a result of comorbid medical illness. Recent advances in the technology to treat early stage disease have led to new-found enthusiasm for treating and studying high-risk patients. This Review focuses on the management of these patients, including use of conformal radiotherapy, stereotactic body radiation therapy, sublobar resection, intraoperative brachytherapy, and radiofrequency ablation. Ongoing challenges are presented and prospective data are emphasised.