Background: Studies on the acute management of extremely low birthweight (ELBW) infants reveal a high incidence of intraventricular hemorrhage (IVH) in infants with high-grade internal cerebral vein perfusion waveform fluctuations. In this prospective observational study we investigated the Doppler perfusion waveform fluctuations in the great cerebral vein, straight sinus, and internal cerebral veins of ELBW infants. Methods: We evaluated perfusion waveforms after birth every 12 h until 120 h in 73 ELBW infants (<1,000 g) at our hospital. Fluctuations were categorized into four patterns of increasing magnitude, Grades 0-3. Results: The maximum grades of perfusion waveform fluctuations of the internal cerebral veins were 0, 1, 2, and 3 detected in 12, 38, 13, and 10 infants, respectively; those of the great cerebral vein were 0, 1, 2, and 3 detected in 5, 17, 20, and 31 infants, respectively; and those of the straight sinus were 0, 1, 2, and 3 detected in 1, 5, 17, and 50 infants, respectively. Only one of 803 simultaneous measurements of the Doppler perfusion waveforms showed stronger fluctuations of the peripheral vein than those of the central side veins. Intraventricular hemorrhage was associated with high-grade fluctuations in the internal cerebral veins but not in the great cerebral vein or straight sinus. Conclusions: Most infants had high-grade fluctuations in the great cerebral vein and straight sinus, with lower grade fluctuations in the internal cerebral vein, but IVH was not associated with those markers. Intraventricular hemorrhage was correlated with high-grade fluctuations only in the internal cerebral veins.