The O2 transport in erythrocytes was shown to depend mostly on the form of erythrocyte, concentration of hemoglobin and its interaction with O2. The O2 transport in microvessels and capillaries depends on distribution of erythrocytes over the blood flow and their velocity, whereas intensity of O2 consumption and architectonics of capillary net determine the velocity and amount of O2 supply in tissues. Study of intricate processes of the O2 transport in microcirculation is only possible when using modern physical-chemical and mathematical techniques revealing the complicated interactions among the parameters under study.