True aneurysms of the pulmonary artery are most frequently associated with congenital heart lesions that have lead to sustained high pulmonary artery flow rates and pulmonary hypertension. A maternal death secondary to a dissecting aneurysm of the pulmonary artery is presented. Death occurred 17 hours postpartum, and the acute dissection may have been precipitated by the high flow rates accompanying parturition or, alternatively, by the Valsalva maneuver. The authors suggest a baseline chest radiograph and electrocardiogram in all women with known or suspected congenital heart disease to evaluate for pulmonary hypertension and pulmonary artery aneurysms. The occurrence of symptoms such as dyspnea or chest pain warrants repeat evaluation with strong consideration being given to right heart catheterization and pulmonary angiography. If a dissecting aneurysm is diagnosed, then emergency surgical repair seems warranted in view of the rapidity with which this condition progresses to death.