Hemodynamic stability and maintenance of cerebral perfusion pressure (CPP) are important in neurosurgical patients. Fluid management includes maintenance of intravascular volume, preservation of cerebral perfusion pressure and minimization of cerebral oedema. Fluid management of the neurosurgical patient has advanced from "run them dry" to "run them isovolaemic, isotonic and iso-oncotic, but the induction of potential complications by current strategies are still unknown. Advanced techniques provide goal directed fluid therapy which is currently the gold standard in fluid strategy. In patients undergoing craniotomy diuretics, preoperative fasting, induction of general anaesthesia and intraoperative bleeding may lead to hypovolemia and poor cerebral perfusion. On the other hand fluid overload increases complications and hospital stay after surgery. It is, therefore, important that optimal fluid levels are achieved.