Although transverse abdominal incisions (TAI) are valued for their excellent exposure in the newborn, infant, and child, measurements to support this clinical impression have been lacking. The abdomens of 80 infants and children and 11 premature infants were measured and evaluated and correlated with growth. It was demonstrated that the younger the child, the relatively larger the abdominal cavity and wall. Because of the anatomical differences between the abdomen of adults and small children, the cavity of the latter resembles a horizontally oriented ellipsoid; accordingly, TAI give greater exposure. The younger the child, the larger proportionately was the costoiliac space, allowing easier lateral extension of the incision, if necessary. The umbilicus is low in infants and small children and the transverse supraumbilical incision may be placed over the anatomical center of the abdominal cavity. The conclusion drawn was that the younger the child, the greater the rationale for routinely employing transverse abdominal incisions.