Primary and secondary lung malignancies are often treated with surgery. Many patients are poor surgical candidates owing to advanced age or medical comorbidities. Alternatives to surgery for localized disease include radiation therapy and the newer treatments known as image-guided thermal ablation. Image-guided thermal ablation involves the use of needlelike applicators that are placed directly into tumors by using imaging guidance. Tumors are destroyed by the application of either intense heat or cold. The specific ablative modalities of radiofrequency ablation, microwave ablation, laser ablation, and cryoablation are reviewed with respect to the various clinical indications for treatment of both primary and secondary lung malignancies.