Chylothorax is a rare cause of pleural effusion in children, and it is usually difficult to identify the location of chyle leakage due to the small size of the thoracic duct in children. Herein we report an infant case with chylothorax whose leakage of the thoracic duct was successfully located by magnetic resonance lymphangiography (MRL) using pre-contrast MR cholangiopancreatography (MRCP) and gadodiamide-enhanced spectral presaturation inversion recovery (SPIR) T1-weighted imaging, which demonstrate the imaging method is easy and effective for detecting the focal disruption of the thoracic duct in children with chylothorax and younger than 8 months old.