The relation of IVH to blood flow velocity in the anterior cerebral arteries has been studied in the premature newborn infant. The objectives of the study were to determine the effect of IVH on cerebral blood flow velocity, measured by a noninvasive Doppler technique, and to assess the reliability of this technique in the diagnosis of the hemorrhage. Thirty-two premature newborn infants with IVH were identified by real-time ultrasound scanning: IVH was present in the first 24 hours of life in approximately 50%, progressed postnatally in approximately 20%, and was severe in approximately 50%. Cerebral blood flow velocity, determined daily in the first five days of life, was compared to the time of occurrence of IVH and to simultaneous measurements of systemic blood pressure and blood gases. No consistent relationship between timing or severity of IVH and cerebral blood flow velocity could be discerned. We conclude that cerebral blood flow velocity in the anterior cerebral arteries is not likely to be affected by IVH and that the noninvasive Doppler technique for measurement of this velocity is not reliable for diagnosis of the lesion.