Solvent induced frequency shifts in the IR absorption and emission spectra were simulated by Monte-Carlo procedure. The pair potential with repulsive, dispersive and electrostatic parts was used to study liquid carbon monoxide at T = 80K and ρ{variant} = 0.7982 g/cm3. It was shown that if single molecule of the system undergoes vibrational transition, the "red" frequency shift in emission spectrum is greater than the one in the absorption spectrum. The computer simulation results predict that if all molecules of the system are excited, the frequency shift of the emitting molecule turns "blue". This means frequency shift in the IR emission spectrum depends on the pumping intensity. The increasing number of excited molecules in the system leads to the increase of the influence of repulsive intermolecular interactions on frequency shift. © 1990.