The endovascular treatment of cerebral aneurysms provides an alternative intervention when the morbidity and mortality rates associated with conventional surgery are excessively high. In cases of giant posterior circulation aneurysms, the morbidity and mortality rates for endovascular treatment rival those of open surgical procedures. Although endovascular treatments provide promise for the treatment of all cerebral aneurysms, present modalities are inadequate to replace existing surgical therapies. The exponential growth in the development of new catheter technologies and thrombotic devices should eventually provide reproducible and permanent occlusion of aneurysm cavities with morbidity and mortality rates that are lower than those of open surgery. Proper intensive care unit management is crucial for success. Protection from rebleeding after endovascular treatment is not guaranteed. Numerous reports of delayed hemorrhage after thrombogenic device placement were described in this review. Remodeling of platinum coils after placement in an aneurysm cavity results in recanalization and possible growth of the aneurysm. It is difficult to consider these patients protected from rebleeding. Recently the Food and Drug Administration prohibited the distribution of silicone balloons in the United States. Negotiations are underway to regain use of these devices. Electrically detachable coils represent a significant advance in the arsenal for endovascular treatment, although this device will not replace open surgery. Future developments in endovascular devices should provide irreversible thrombosis of cerebral aneurysms regardless of their size, configuration, or position.