Laser-magnetic field action on blood in vivo was studied within a range 440-650 nm. The primary mechanisms of laser-magnetic
blood irradiation in vivo were studied at (1) laser and non-laser irradiation with light of various wavelengths,
(2) autohemo-magnetic-therapy, (3) multicolored over-vein irradiation of the blood, (4) the laser-magnetic field actions.
Hemoglobin is considered as primary photoacceptor of radiation. The dependence of effectiveness of laser action on
light wavelength was compared with known action spectra for blood photostimulation. Magnetic field enhancement of
the laser- induced reactions was discussed as result of magnetic field influence on ferromagnetic hem inclusions and on a
structure of hemoglobin peptide chains. Hemoglobin oxygenation or deoxygenation processes were analyzed as a first
stage of the therapeutic effects depending on a preceding hemoglobin oxygenation degree at pathological state. The laser-
magnetic irradiation causes tendency to the normalization of these process. It is proposed that the secondary reactions
are initiated by reversible structural changes of erythrocytes membrane caused the strong hemoglobin absorption.