This work focuses on styding the effect of recombination losses on the efficiency of thin-film solar cell based on CIGS. The results have been carried out based on the width of the space-charge region, thickness of the absorber layer, lifetimes of charge carriers and recombination velocity at the front and back surfaces. The recombination losses in thin-film solar cells based on CIGS have been evaluated quantitatively. The determination of the recombination losses is carried out on the basis of the continuity equation taking into account the drift and diffusion components of the photocurrent. It is found that the thickness of the absorber layer has a significant effect on the values of short-circuit current density more than the effect of the width of the space-charge region. The front surface recombination losses increased with widening W while the back surface recombination losses can be neglected particularly at thick layer of the absorber. The minimum recombination losses of 3% have been achieved for dCIGS>2 μm and W=0.3 μm. At certain parameters of the used materials and with taking into account recombination losses, the efficiency of CIGS records a value about 25%.