Cerebral blood flow (CBF) and carotid blood flow (CAF) during open-chest cardiac massage with and without occlusion of the descending aorta was examined in 10 dogs to assess whether they were augmented by occlusion. In control measurements with a normally beating heart, CBF with and without occlusion of the descending aorta were 17.8 +/- 2.3 and 13.8 +/- 2.2 ml/min (+/- S.E.M.), which were not significantly different. Cerebral blood flow during open-chest cardiac massage were 6.1 +/- 1.0 with occlusion and 5.7 +/- 1.0 ml/min without occlusion of the descending aorta, which were also not significantly different. By contrast, CAF increased significantly with occlusion of the descending aorta both during control measurement, with mean increases of 61.1% and 92.2% during open-chest cardiac massage (P = 0.05). While occlusion generally failed to augment CBF; in two dogs resuscitation was successful by manual cardiac massage. With the restoration of cardiac activity it increased immediately to twice that of control blood flow, and then gradually returned to the control level. Based on these observations, it is the author's opinion that every effort should be directed toward the restoration of cardiac activity as quickly as possible during circulatory arrest, and to increase CBF which is essential for neurological recovery.