We investigated the effects of pulsatile flow for retrograde cerebral perfusion under profound hypothermia. Total cardiopulmonary bypass was carried out in adult mongrel dogs to induce hypothermia. One hour of total circulatory arrest was then performed at 20 degrees C in the control group of 6 dogs. In another group of 6 dogs, after cardiac arrest was obtained at 20 degrees C, retrograde cerebral perfusion with nonpulsatile flow was performed through both sides of the internal maxillary vein for 60 minutes; in a third group of 6 dogs, retrograde pulsatile perfusion was continued for 60 minutes. At the end of either retrograde perfusion or total circulatory arrest for 60 minutes, cerebrospinal fluid pressure and blood flow in the cerebral tissues were measured, and cerebral tissues were collected to measure water and adenosine triphosphate content. A significant difference was found for water content between the group undergoing retrograde perfusion with pulsatile flow as opposed to nonpulsatile flow. Cerebral tissues in the group perfused retrogradely with nonpulsatile flow contained more water than in the group perfused with pulsatile flow. Cerebrospinal fluid pressure was lower in the group perfused retrogradely with pulsatile flow when compared with nonpulsatile flow, but no significant difference could be found. As for cerebral flow and adenosine triphosphate content, no significant differences could be found between the groups perfused retrogradely with pulsatile or with non-pulsatile flow. Values were always higher, nonetheless, in the groups perfused with pulsatile flow. We conclude that retrograde cerebral perfusion with pulsatile flow, when used under conditions of profound hypothermia, possesses more cerebroprotective effects than does non-pulsatile perfusion or circulatory arrest.