Although chylothorax is a well-described complication of malignancy, especially lymphoma, breast adenocarcinoma has not been a commonly implicated primary tumor. There has been only one published report of biochemically confirmed bilateral chylothorax in solid malignancy, and this was not associated with breast adenocarcinoma. Likewise, there has been only one published report of bilateral chylothorax in solid malignancy with positive pleural fluid cytology on both sides; again, the primary tumor was not breast adenocarcinoma. Herein we present a case that combines all three of these rarely reported features: a patient with metastatic breast adenocarcinoma who developed biochemically confirmed bilateral chylothorax with documented positive pleural fluid cytology on both sides. This report is accompanied by a literature review of published cases of bilateral chylothorax in solid malignancy.