The convective transport of oxygen by blood and the diffusion path of its delivery from blood to tissue are considered. The role of the oxyhemoglobin dissociation rate in providing the oxygen demand for tissues at different intensities of metabolic processes is discussed. Data on the magnitude of the oxygen tension in the blood, the longitudinal and radial gradients values in various vessels and extravascular spaces of various tissues are provided. The arterioles and capillaries role in the oxygen diffusion in the tissues and between the vessels of the microvasculature and the oxygen consumption by cells of various layers of the arteriole wall is discussed. Sоme basic aspects of regulating the oxygen blood transport and diffusion from blood to tissue are described.