Optical constants - extinction coefficient, absorption coefficient, and phase function - of bovine liver were measured. A dye laser, was tuned from 5770Å to 5870Å, and He-Ne laser were used as light source. Exitinction coefficient was evaluated from the measured slope of In(I/$I_0$) to the sample thickness. Absorption coefficient is measured using an integrating sphere which was operated in error range 7%. The extinciton coefficient of the bovine liver was 278 ± 21 $cm^{-1}$ and the absorption coefficient was 21 ± 5 $cm^{-1}$ in the measured wavelength region. The mean cosine of scattering angle was 0.9. The distibution of the light flux in the bovine liver at 5848Å was calculated using 1-D approximation theory with Groenhuis phase function. A high albedo, 0.93, was observed, meaning a strong scattering of incident laser light.
