Endovascular neurosurgery is a relatively new field that is evolving at a rapid pace. The specialty is driven by new technologies that allow us to approach increasingly difficult problems. In recent years, the Guglielmi detachable coil system has moved to the forefront of endovascular approaches to the treatment of intracranial aneurysms and has practically replaced several previous endovascular approaches to most of these lesions. Open craniotomy with clipping is still the treatment of choice when the neurosurgeon feels the risks are acceptable and the patient is an appropriate candidate. However, the indications for the endovascular approach are expanding as long-term outcome data accumulate. We are now beginning to define specific subsets of patients in whom endovascular treatment may be a more attractive option than open surgical clipping. More recently, new ideas about aneurysm architecture have been described that may contribute to predicting long-term outcomes with endovascular treatment.