Chylothorax indicates the accumulation of chyle in the pleural cavity. It is a rare cause of pleural effusion, especially bilaterally. In clinical practice, the presence of milky fluid in the pleural cavity raises the suspicion of chylothorax. The most common cause is trauma, iatrogenic or non, owing to thoracic duct injury, which transports chyle from the lymphatic system into the bloodstream. The case we describe is of a 53-year-old female who was referred to our hospital with bilateral pleural effusions and a left supraclavicular mass. From the diagnostic studies, the nontraumatic causes of chylothorax were excluded. The potential diagnosis was traumatic chylothorax, a diagnosis of exclusion, as it appeared after muscle stretch and receded with a fat-free diet and repose without any relapse.