FIELD : medicine.SUBSTANCE : invention relates to medicine. Method of measuring degree of blood saturation with oxygen and carbon monoxide in an object of investigation is carried out by means of an optical measuring device. Device comprises : an optical lens mounted on the optical axis of the device and having a first focal point in the object space and a first and a second focal point; two optical radiation sources emitting rays with different wavelengths; a point diaphragm installed in the first plane, centred relative to the first focal point of the lens in the image space, and a point diaphragm installed in the second plane centred relative to the second focal point in the object space, photosensitive receiver designed to receive optical beams from a first focal point in the image space and located along the beam path behind the point diaphragm, a flat semi-reflecting mirror configured to direct rays emitted by the two optical radiation sources, to a lens and for transmitting beams from a first focal point in the object space to a photosensitive receiver, a control unit configured to analyse optical beams received by the photosensitive receiver and to compare the analysis results with known data. Method includes the following operations : installing an optical measuring device facing the surface of the skin of the test object to a predetermined position, in which the first focal point of said lens in the object space is located at a predetermined depth in the skin layer, enabling the optical beams to be emitted by the two optical radiation sources to the second focal point in the image space at the predetermined depth in the skin layer, by means of a photosensitive receiver, optical beams emitted by two optical radiation sources reflected by the skin and emanating from the first focal point in the objects space, located at a predetermined depth in the skin layer, degree of skin absorption of optical beams emitted by two optical radiation sources is determined based on analysis results of optical beams received by the photosensitive receiver, and the degree of blood saturation with oxygen and carbon monoxide in the test object is determined from the measured degree of absorption.EFFECT : using the given invention enables higher accuracy of measuring a physiological parameter.1 cl, 2 dwg