Mean arterial and venous CBFV (cm/sec) were measured simultaneously by Doppler Velocimetry of the Antetion Cerebral Artery and Internal Cerebral Vein in 3 groups of newborn infants of various Gestational Ages (GA, w), Birth Weights(BW,g) and Post-Natal Ages (PNA,d) Group 1, 53 normal infants, GA 26-41 w, BW 950-3890 g, PNA 1-60d: Group 2, 27 infants with RDS treated with different levels of CPAP, GA 26-34w, BW 830-3130g, PNA 1-30d: Group 3, 18 infants with IPIE, GA 32-42w, BW 1180-3750g, PNA 1-3d, diagnosis of IPIE was based on the following criteria: need for vigorous resuscitation at birth; severe acidosis (BD 12 and pH 720) within one hour of age: clinical evidence of Grade 2 in 3 IPIE by Same classification (*)In infants of Group 1, mean arterial and venous CBFV were GA and PNA dependent, To they measured significantly (p<0.01) with both GA and PNA. In infants of Group 2, mean venous CBFV (but not arterial CBFV) decreased significantly (p 0.01) with increasing CPAP by approximately 1 cm/sec H2O CPAP movement In infants of Group 3, mean arterial and venous CBFV were considered “abnormal” when higher or lower than 2 SO from the average noraml values obtained in infants of Group 1 By these criteria, 6 infants with both “abnormal” arterial and venous CBFV all had a severe outcome, ie 4 died and 2 land severe neurological abnormalities at follow-up; bone of the 12 infants with both “normal” (7)or just one “normal” (5) CBFV either died of became severely handicapped The present study providers normal reterence values of arterial and venous CBFV in the newborns of suggests that monitoring of mean venous CBFV in infants with RDS could provide useful information on the possible interference of excessive CPAP on the cerebral circulation: finally, it suggests that the simultaneous evaluation of both arterial and venous CBFV is a better medication of severe outcome in infants with IPIE than the measurement of arterial CBFV alone (*)Samat H B and Samat N S Arch Neurol 1976:33 696-705