Objective: To study the therapeutic effect of nimodipine on experimental brain injury.Methods: Experimental and control rabbits were subjected to a closed head injury. In one group nimodipine was given intravenously and the effect evaluated by electron microscopy, brain water content, calcium levels, transcranial Doppler, and intracranial pressure monitoring.Results: In rabbits treated with nimodipine the level of neuronal cytosolic free calcium was markedly decreased. There were less cellular damage and less spasm of the middle cerebral artery seen on electron microscopy. No difference regarding intracranial pressure changes between the two groups was noted. Conclusions: Nimodipine has a protective action on brain injury by blocking a series of pathological reactions induced by neuronal calcium overload, and by reducing the spasm of brain vessels and improving cerebral blood flow.