Brain ischemia triggers a complex cascade of molecular events that unfolds over hours to days. Identified mechanisms of postischemic neuronal injury include altered Ca²⁺ homeostasis, free radical formation, mitochondrial dysfunction, protease activation, altered gene expression, and inflammation. Although many of these events are well characterized, our understanding of how they are integrated into the causal pathways of postischemic neuronal death remains incomplete. The primary goal of this review is to provide an overview of molecular injury mechanisms currently believed to be involved in postischemic neuronal death specifically highlighting their time course and potential interactions. [Neumar RW. Molecular mechanisms of ischemic neuronal injury. Ann Emerg Med. November 2000;36:483-506.]