Abstract: Device and method for treating vascular defects by filling the defect with magnetically controlled devices. Vascular defects include aneurysms and arteriovenous malformations (AVMs), particularly in the head and neck of the patient. The magnetic devices fall into categories of ferro-fluids, magnetic objects and magnetic coils. Ferro-fluids consist of a magnetic particulate that is combined with a glue or polymer agent. The ferro-fluid is magnetically held and solidified, while the adhesive agent cures. Magnetic objects such as polyvinyl alcohol (PVA) coated magnetic particles can be injected into a vascular defect such as an AVM. The magnetic objects are attracted into pre-selected AVM branches by the application of a magnetic gradient. Magnetic coils are magnetically steered and held within an aneurysm to improve coil delivery. Large neck aneurysms are particularly assisted by this method, due to the need to steer the coil towards the center of the aneurysm and to hold the coils within the aneurysm.