Timing of surgery is one of the most important and controversial aspects in the management of the patient with a ruptured aneurysm. For each patient with a ruptured aneurysm, the treating physician is faced with a difficult decision: to operate acutely in order to avoid rebleeding despite the swollen brain, or to wait until the effects of the initial hemorrhage subside. The decision of whether or not to perform surgery acutely after subarachnoid hemorrhage (SAH) strongly affects the ability to prevent and treat some of the complications of SAH. Either approach, early or delayed surgery, has pros and cons. This article reviews the numerous factors that play a role in this delicate decision-making process.