We report an unusual case of the left sided diaphragmatic hernia in which the left lobe of the liver blocked the herniation of the intestinal contents into the chest and the clinical symptoms were not apparent at birth. The patient was a full term infant born to a mother whose antenatal care included apparently normal sonographic evaluation. She developed increasing tachypnea within two hours period after birth. Auscultation of the chest revealed bilateral normal aeration. No cardiac murmurs were heard. An X-ray of the chest revealed a left sided haziness without any mediastinal shift. Progressive decrease in the breath sounds was noted over the left base. A CT examination demonstrated a left sided diaphragmatic hernia, with herniation of the left lobe of the liver causing compression of the lung. No loops of the bowel were observed in the thoracic cavity. She underwent laparotomy and repair of diaphragmatic hernia. This case history illustrates that large left sided diaphragmatic hernias may be missed on antenatal sonogram and may not present with clinical signs until several hours after birth. Both physical examination and routine chest X-ray may prove inconclusive and a CT scan is necessary to make a definitive diagnosis.