The dielectric function of CuInSe2 has been studied for various composition ratios of Cu/In. The crystals were cut from ingots of 10mm. diameter and 40mm. length, grown by the classical Bridgman method. Spectroscopic ellipsometry measurements have been performed at room temperature in the range of 1.5-5.5eV. From the measured spectra of the imaginary part of the dielectric function epsilon (2), the broadening effect of the Cu/In ratio has been examined in connection with photoluminescence measurements. All transition edges were found to broaden as the In content increases. The effect of copper d levels has been observed to dominate in the 2.5-3.5 eV range.