The authors present the technical aspects of perioperative safety during the microsurgery of cerebral aneurysms. We evaluated the advantages and disadvantages of the microvascular Doppler ultrasonography, the intraoperative digital subtraction angiography, the intraoperative transit time flowmetry, the intraoperative monitoring - motor evoked potentials and somatosensory evoked potentials, and the ICG videoangiography. The authors, based on their own experience, recommend combining different methods to eliminate the weak points of the individual specific methods. Combining the ICG with the flowmetry and the motor evoked potentials enhances safety during the surgery of cerebral aneurysms with the resultant reduction of the perioperative morbidity/mortality.