The larynges of 27 infants weighing between 250 gm and 9160 gm were studied. Twenty-two neonates were from 24 to 40 weeks' gestational age. Five subjects died more than 6 weeks post partum but were included because of their small size. Relationships of larynx size to the standard clinical measurements of crown-heel length, crown-rump length, head circumference, and gestational age were developed. Cartilage size relationships to these measurements were found to be linear. Glottic length related linearly to crown-rump length but related in a curvilinear way to crown-heel length, head circumference, and gestational age. A guide to the choice of endotracheal tube sizes for small infants is suggested.