Small caliber needle aspiration of lung lesions has been successfully and safely used for diagnostic purposes. We report our initial experience using computed tomography-guided fine needle percutaneous implantation for direct intralesional high-dose rate brachytherapy for malignant pulmonary lesions. Twenty patients with primary lung cancer or metastatic cancer which involved the lung or chest wall were treated with a high-dose rate remote afterloader. Eighteen of the 20 patients also received external beam radiation in conjunction with intralesional radiation therapy. Fourteen patients had primary lung cancer. A complete response was obtained in 5 of the 14 patients. Ten of the 14 patients with primary non-small-cell carcinoma of the lung showed a significant response to treatment (greater than 50 percent reduction in tumor measurement). Six patients with metastatic lesions also were treated. Five of the six showed a significant tumor response measured as either 50 percent reduction in tumor measurement or complete pain relief. The only significant complication was pneumothorax (6 of the 20), which did not prevent completion of any treatment plan.