We assessed the ability to maintain cerebral blood flow (CBF) when intracranial pressure (ICP) is raised under normoxic and isocapnic hypoxic conditions in pentobarbital-anesthetized neonatal lambs (3-9 days old). ICP was increased by infusion of artificial CSF in the lateral ventricle to produce 8 mmHg stepwise decrements in cerebral perfusion pressure (CPP) from baseline (&asymp 66 mmHg) down to a CPP of approximately 26 mmHg. In one group (n=6) of normoxic lambs (arterial O2 content (CaO2) = 14.8 ± .7 ml/dl), CBF (ml·min “100g−1; microspheres) was unchanged from baseline (49 ± 7) down to a CPP of 34 mmHg (47 ± 6). At a CPP of 26 mmHg, CBF was decreased to 37 ± 5. In another group (n=6) of hypoxic lambs (CaO2 = 7.6 ± .9 ml/dl; 49 ± 4% arterial O2 saturation) baseline CBF (87 ± 11) was nearly twice that of the normoxic group. CBF was not significantly changed down to a CPP of 34 mmHg (78 ± 8), but was decreased at a CPP of 26 mmHg (73 ± 8). Cerebral fractional O2 extraction (measured at sagittal sinus) was also maintained down to a CPP of 34 mmHg in both groups before it rose at 26 mmHg. Cerebral O2 uptake was not different between groups and was not diminished with elevations of ICP in either group. We conclude that a) neonatal lambs are capable of CBF autoregulation with increasing ICP, and b) hypoxia sufficient to double baseline CBF but not diminish O2 uptake does not impair CBF autoregulation.