OBJECTIVE: To determine the efficacy and safety of early intervention with nimodipine treatment in diffuse axonal injury. METHODS: Based on the characteristic radiological signs and criteria for diffuse axonal injury (DAI), 89 patients with the diagnosis of DAI were enrolled in this randomized, double-blind, placebo-controlled trial. RESULTS: Nimodipine proved to be safe and well tolerated. With TCD sonography we found that there was a higher incidence of cerebral vasospasm in this series (38.2%). Overall, Nimodipine produced a better clinical result than placebo, but there was no statistically significant difference in favorable outcome at 3 months after injury (P=0.11) between the two groups. A trend toward a favorable effect was suggested by the analyses in two small subgroups, either in the patients suffering from clinical Grade III DAI (P=0.04), or in those with the TCD-evidence of cerebral vasospasm during clinical observation (P=0.049). CONCLUSIONS: We postulate that a clinically valuable benefit is possible with nimodipine treatment in DAI patients. However, the effects on outcome should be verified by further controlled study.