Some quantitative clinical method for predicting survival of the neonatal period would be helpful to clinicians and investigators alike. At present, most clinicians rely on birth weight and an appraisal of the infant in qualitative terms at some unselected period following birth for their prognosis. The most important aspect of survival in this age period is the respiratory exchange of O2and CO2. Birth weight does not directly reflect this function. Qualitative terms, such as asphyxia pallida and livida, cyanosis, dyspnea, hypotonia, and tachypnea are so replete with the subjective interpretation of the observer as to make comparisons between sick and healthy infants in the same or separate clinics possible on only general terms. Two groups of investigators have recently attempted to develop clinical methods that would reflect respiratory function in meaningful, quantitative terms, thus removing some of the guesswork from their appraisals. Apgar and her group,1