Recent experimental and clinical studies of cardiac arrest, suggesting a brain damage ameliorating effect of thiopental loading, stimulated the development of an international randomized clinical trial of brain resuscitation. Twelve collaborating hospitals in 9 countries are testing the efficacy of post-cardiac arrest thiopental loading (30 mg/kg body wt). The methodology for assessing insult and outcome data, as well as risk and benefit monitoring, is described. This clinical trial will be completed in 1983 and is expected to provide valuable data about the efficacy of thiopental loading. The study mechanism is now well-established and ready for the evaluation of future promising brain resuscitation therapies.