Ferrofluids having magnetic particles dispersed therein are introduced locally via a catheter, a micro-catheter, or intravenously, to the bloodstream of a patient. The ferrofluids are magnetically manipulated or moved throughout the blood vessels of the patient by an external magnetic field generator until the intended occluding thrombus is broken up and removed. The external magnetic field generator, which can be stationary or portable, creates a vortex, high velocity jets, or other motion, within the ferrofluids, by rotating or moving at least one magnet (21) relative to the patient. The at least one magnet is provided in the magnetic field generator. The vortex, high velocity jets, or other motion of the ferrofluids are used to break-up and remove the occluding thrombus. Drugs or abrasive particles, or both, may be incorporated with the ferrofluids and delivered to the bloodstream with the ferrofluids to help break-up and remove the occluding thrombus as well.
