We report a case of chylothorax which appeared in a mother after childbirth. Disruption of the thoracic duct occurred with the high intrathoracic pressures generated by the Valsalva maneuver used by the patient during labor to "push." No evidence of other trauma or malignancy were found and the patient did well after use of total parenteral nutrition, thoracotomy with thoracic duct ligation, and pleurodesis.