Transmittance spectra and spectra of optical loses due to absorption and scattering of different,biofluids were registered by spectrophotometer DU-64 Beckman in the range of wavelength from 200 to 900 nm. The alteration of spectra of blood serum and whole blood were observed after irradiation of the samples by laser light (633 or 850 nm). The preliminary results indicating that the laser effects depend on the initial biophysical and biochemical state:of blood are discussed.