α-Phellandrene is a cyclic monoterpene that has been found in various plants, including Cannabis, and has diverse biological activities. In vivo, α-phellandrene (50, 100, and 200 mg/kg, p.o.) reduces carrageenan-induced neutrophil accumulation and leukocyte rolling and adhesion as well as inhibits production of the pro-inflammatory cytokines TNF-α and IL-6 in a rat model of air pouch inflammation. It decreases spleen weight and increases macrophage phagocytosis and natural killer (NK) cell cytotoxic activity in a murine WEHI-3 leukemia model. α-Phellandrene has antinociceptive effects in mouse models of pain, reducing acetic acid-induced writhing, paw licking in the capsaicin test, and glutamate-induced licking and biting behavior, as well as increases the paw withdrawal threshold following carrageenan-induced inflammation.