The aim of this work was to investigate the optical behavior of bioceramics used for dental restorations by Kubelka-Munk (K-M) model. Samples of a vacuum-sintered porcelain and three ceramic composites (Al2O3, Al2O3-ZrO2, MgAl2O4) infiltrated with glass were prepared. Reflectance was measured in spectrophotometer using white and black backgrounds. Scattering (S) and absorption (K) coefficients, determined by K-M model, varied significantly among the investigated materials. In all bioceramics, K value diminished strongly, while S value increased or remained almost constant, with the increase in wavelength. In general, S value increased with the decrease in the material’s transparency, but similar tendency was not observed for K value. The optical properties were correlated with the material’s microstructure and average mean path for light propagation. The results indicated that the scattering was the dominant mechanism that determined the light transmission in the investigated materials, but, in low wavelength range, the absorption also affected significantly.