This article describes the rationale behind the use of systemically administered lidocaine as an analgesic. The analgesic efficacy of intravenously administered lidocaine is well documented by studies in human patients and laboratory animals. The mechanism by which systemically administered lidocaine produces analgesia is uncertain but is thought to include action at sodium, calcium, and potassium channels and the N-methyl-D-aspartate acid receptor. In addition, the anti-inflammatory actions of lidocaine are important in producing analgesia because inflammatory mediators augment neuronal excitability. The available studies of systemically administered lidocaine in horses provide evidence for the analgesic and anesthetic effects of intravenous lidocaine in this species.