Dexanabinol (HU-211) is a synthetic non-psychotropic cannabinoid and a non-competitive NMDA-receptor antagonist. The beneficial effect of dexanabinol on prevention of degeneration and promotion of regeneration was studied on the crush-injured rat optic nerve model. Sprague-Dawley rats were subjected to a calibrated crush injury of the optic nerve and treated with a single intraperitoneal injection of dexanabinol (7 mg/kg), its vehicle only or were untreated. Transmission electron microscopic analysis of the excised optic nerves was performed after 30 days. In the dexanabinol treated rats, the site of injury was traversed by unmyelinated and thinly myelinated axons, possibly indicative of regenerative growth. No such growth was detectable in the controls. Viable axons were found 0.5 mm distal to the site of injury in 6 of 8 dexanabinol treated rats, but in only 1 of 10 rats in the control groups. These results have clinical implications for the prevention of secondary degeneration and promotion of regeneration after injuries to the central nervous system.