The fundamental isotropic Raman Q-branch of CO has been recorded using Raman loss spectroscopy for mixtures with helium at low temperatures (77-195 K). Accurate close coupling calculations of both diagonal and off diagonal (line coupling) cross sections have been performed starting from one of the best available potential energy surfaces [T. G. A. Heijmen, R. Moszynski, P. E. S. Wormer, and Ad van der Avoird, J. Chem. Phys. 107, 9921 (1997)]. Predictions are in good agreement with Q-branch Raman data. These results, which corroborate previous analysis based on IR absorption data, are a further test of the adequacy of the close coupling formalism for the prediction of line shapes in a rather wide range of physical situations (pressure, temperature, type of spectroscopy...), when an accurate potential exists.