Congenital defects of lymphatics in infancy are manifested by chylous ascites, chylothorax and lymphedema. One case of congenital chylous ascites and two cases of congenital chylothorax, are added to the literature. Eight cases of [See FIG. 11. in Source Pdf.] congenital lymphedema are reviewed from the hospital records with a follow-up study. No mention of combinations of these manifestations was found in the literature. A case report of chylous ascites with lymphedema is presented and some experimental work is presented in a case of lymphedema with chylous ascites and chylothorax. Numerous large lymphatic spaces were present in the intestinal mesentery, serosa and bowel villi. The subcutaneous tissues of the involved limbs showed many dilated lymphatic channels. The uninvolved limbs showed similar, but less extensive, changes. The pathologic picture is one of multiple dilated lymphatic channels, with failure of peripheral channels to communicate with the larger lymphatics. Experimental evidence is provided to show that the chyle in the thoracic and abdominal cavities can be explained by a back pressure phenomenon of parietal and visceral lymphatics rather than small breaks in the thoracic duct which we were unable to demonstrate. In the past, hypoplasia and absence of the thoracic duct, has been postulated in cases of chylothorax. This work does not support that view.