A method and device for noninvasive measurement of blood component concentrations utilizes pulsed polychromatic light source emitting, light in the near infrared range 800-1850 nm. The light is back scattered from or transmitted through a part of a patient's body. Back scattered light from blood-containing tissues and blood vessels has information on blood component concentrations. That light is collected to avoid the surface reflection from the skin surface and to minimize the effects of changes in the scattering background. The concentrations of blood components are calculated from the spectral analysis based on selected wavelengths by a defined algorithm. A microprocessor calculates and determines the blood component concentrations by comparing a ratio with a calibration curve stored in a memory of the microprocessor. The calculated concentration values are displayed on a display.