A system (40) is presented for correction of a patient's biological fluid, such as his blood, lymph or spinal fluid, containing various low-, medium- and high-molecular toxins. The system (40) comprises an extracorporeal flow line in the form of a flexible tube interconnected between outlet and inlet means (44, 46) attached to appropriate location(s) on a patient's body. A small amount of the biological fluid, i.e., substantially not exceeding 100ml, substantially continuously flows through the tube, and is mixed with magneto-conductive particles capable of adsorbing the various toxins. An obtained mixture of the biological fluid with the particles passes through a magnetic field region (70), and substantially all of the magneto-conductive particles are retained therein. Particle-free biological fluid is then returned into the patient's body through the inlet means (46).