['To identify the value of unilateral pedal lymphangiography (LAG) with non-contrast CT in the location and treatment decision of idiopathic chylothorax after failure of thoracic duct ligation.', 'Twenty four patients aged 9-84 year old (median 44 yr) who had idiopathic chylothorax were involved, and unilateral pedal LAG with non-contrast CT was performed in every patient. All patients failed to previous right supra-diaphragmatic thoracic duct ligation.', 'The amount of iodized oil used was 6-14 ml with no related complications. LAG demonstrated 8 patients with thoracic duct leaks and 10 patients with leaks elsewhere, but no visible chylous leak in 6 patients. Ligation of thoracic duct was performed as the primary treatment in all 8 cases as having thoracic duct leakage and cured 7(87.5%) patients. For 8 patients not having thoracic duct lesion under LAG, the successful rate of thoracic duct ligation was 25% (2 out of 8 patients), which was significantly lower than patients due to thoracic duct lesions (P=0.02). Meanwhile, non-operative therapy had significantly higher successful rate (87.5% vs 25%, P=0.02).'] Is unilateral pedal lymphangiography with non-contrast computerized tomography valuable in the location and treatment decision of idiopathic chylothorax?