My purpose in this paper is to describe a simple procedure for the early diagnosis of congenital atresia of the esophagus or intestine by means of microscopic examination of the meconium. Congenital atresia of the intestine has been recently treated in its various aspects by Ladd.1He emphasizes the great importance of early recognition and surgical intervention. The methods of roentgenologic diagnosis of esophageal atresia have been described by Vogt.2 The procedure I am reporting has proved of value and has the advantages of simplicity and accuracy. It is based on the well established fact that a considerable part of the bulk of meconium is made up of swallowed amniotic sac contents. Amniotic sac contents, in addition to the amniotic fluid, consist of vernix caseosa, lanugo hair and cornified epithelial cells, all derived from the skin of the fetus. The origin of meconium, according to Feldman,3is