A Monte-Carlo simulation was carried out to study the influence of lateral interactions on the infrared spectrum of CO molecules adsorbed on the (10{A figure is presented}0) face of ZnO. The interactions are shown to cause a fine structure of the adsorbed CO band which reflects the arrangement of particles in the adlayer. Changes in the spectra with surface coverage are in agreement with the experimental data. For saturating coverage a contour of the CO band can bear information about the defects or disruptions in the adsorbed layer.