β-Caryophyllene (trans-4,11,11-trimethyl-8-methylenebicyclo[7,2,0]undec-4-ene), found in various plants, is a natural bicyclic sesquiterpene with a low toxicity. Here, we show that a single intraperitoneal injection of β-caryophyllene (10 mg/kg) significantly reduced the cortical infarct volume by 67% when given immediately before middle cerebral artery occlusion (MCAO). Neurological deficits caused by MCAO were also significantly decreased by β-caryophyllene. β-Caryophyllene treatment of cortical cells exposed to oxygen-glucose deprivation revealed a significant protection in a dose-dependent manner. However, β-caryophyllene neither suppressed N-methyl-D-aspartate excitotoxicity in cultured cortical cells nor markedly decreased the oxidative stress measured in the cellular or acellular systems. By contrast, treatments with β-caryophyllene dose-dependently inhibited mRNA expression of inducible nitric oxide synthetase, interleukin (IL)-1β, IL-6, and cyclooxygenase 2 in C6 microglial cells, and decreased the level of nitric oxide and prostaglandin E₂ at a 100 μM concentration. All of these findings suggest that β-caryophyllene has a potent neuroprotective activity, and its neuroprotection may be partly related to the modulation of inflammatory mediators.