Leukotrienes are a group of noncyclized fatty acid eicosanoids which are formed from the breakdown of arachidonic acid. They are potent mediators of inflammation and may contribute to secondary injury in the central nervous system. All mammalian tissue including cerebral cortex is capable of synthesizing these; however, clear documentation of leukotriene formation in the spinal cord is lacking. We subjected 55 rabbits to weight drops of 200, 300, and 400 gm/cm, respectively, on an exposed spinal cord. The traumatized spinal cord was removed after periods of 15, 30, and 45 minutes and 1, 2, 4, 8, and 24 hours. Radioimmunoassay for leukotriene B-4 was then performed on the specimens. Significant (p less than 0.05) elevation was noted in the 200 and 300 gm/cm groups with peak levels occurring in the first 4 hours. The 400 gm/cm group showed significant depression of values below control levels from 2 to 24 hours. We conclude that in sublethal central nervous system injury leukotrienes are produced in significant amounts and may contribute to secondary spinal cord injury.