Prophylactic use of hypervolemia and hypertension is believed to present an option to decrease the incidence of symptomatic vasospasm after aneurysmal subarachnoid hemorrhage and improve neurologic outcome. A Medline literature search was conducted to review available evidence regarding volume management after subarachnoid hemorrhage. Quality of selected studies was evaluated, using the standardized GRADE system. Eleven studies focused on prophylactic hypervolemic therapy after aneurysmal subarachnoid hemorrhage were identified, including four randomized controlled trials. Available studies showed a large heterogeneity in physiologic treatment goals and interventions applied. The oldest and smallest randomized controlled trial suggested a positive effect, but had severe limitations in trial design. Neither of the other randomized controlled studies showed outcome benefit with hypervolemic therapy. Results from observational studies were not found to support the use of prophylactic hypervolemia and hypertension. Complication frequency was repeatedly reported to be higher with the application of prophylactic hypervolemia. In summary, prophylactic hyperdynamic therapy after subarachnoid hemorrhage has not been adequately shown to effectively raise cerebral blood flow or improve neurological outcome. In contrast, there is evidence for harm using overly aggressive hydration.