The optical properties (absorption and reduced scattering coefficients, μa and μs') of bovine liver tissue for 635 nm have been determined by using integrating sphere and inverse adding-doubling (IAD) techniques. For this purpose, total reflectance and total transmittance values of bovine liver tissue sample, which is placed between two microscope slides, have been measured by using single-sphere system. The measured values have been used as input parameters for IAD program to extract the µa and μs' of the sample. In this study, μa and μs' of bovine liver tissue for 635 nm have been determined to be 0.22 mm-1 and 0.51mm-1, respectively. These values, which yield 1.44 mm penetration depth, are in good agreement with the ones in the literature. [ABSTRACT FROM AUTHOR]