Chylothorax is bacteriostatic in nature. Bacterial infection rarely develops in chylothorax and has never been reported in a non-immunocompromised host. A 33-year-old woman was admitted to National Taiwan University Hospital because of fever and right pleuritic pain. Chest roentgenography and computed tomography revealed right pleural effusion. Examination of the pleural effusion revealed a profile compatible with empyema and chylothorax. Culture of the pleural effusion yielded Streptococcus agalactiae. The woman was not immunocompromised. This is the first report of infected chylothorax caused by Streptococcus agalactiae in a non-immunocompromised host.