Necrostatin-1 inhibits receptor-interacting protein (RIP)-1 kinase and programmed necrosis and is neuroprotective in adult rodent models. Owing to the prominence of necrosis and continuum cell death in neonatal hypoxia-ischemia (HI), we tested whether necrostatin was neuroprotective in the developing brain. Postnatal day (P)7 mice were exposed to HI and injected intracerebroventricularly with 0.1 μL of 80 μmol necrostatin, Nec-1, 5-(1H-Indol-3-ylmethyl)-(2-thio-3-methyl) hydantoin, or vehicle. Necrostatin significantly decreased injury in the forebrain and thalamus at P11 and P28. There was specific neuroprotection in necrostatin-treated males. Necrostatin treatment decreased necrotic cell death and increased apoptotic cell death. Hypoxia-ischemia enforced RIP1-RIP3 complex formation and inhibited RIP3-FADD (Fas-associated protein with death domain) interaction, and these effects were blocked by necrostatin. Necrostatin also decreased HI-induced oxidative damage to proteins and attenuated markers of inflammation coincidental with decreased nuclear factor-κB and caspase 1 activation, and FLIP ((Fas-associated death-domain-like IL-1β-converting enzyme)-inhibitory protein) gene and protein expression. In this model of severe neonatal brain injury, we find that cellular necrosis can be managed therapeutically by a single dose of necrostatin, administered after HI, possibly by interrupting RIP1-RIP3-driven oxidative injury and inflammation. The effects of necrostatin treatment after HI reflect the importance of necrosis in the delayed phases of neonatal brain injury and represent a new direction for therapy of neonatal HI.