Electron-Impact Excitation of the B ^1SIGMA^+, C^1SIGMA^+ and E^1PI States ofElectron impact excitation of CO plays an important role in planetary atmospheres andinterstellar clouds. At the present time, serious discrepancies exist among excitation cross sectionsreported in the literature for this molecule. We measured electron impact excitation cross sections forB^1SIGMA^+right arrowX^1SIGMA^+, C^1SIGMA^+right arrowX^1SIGMA^+ and E^1PIrightarrowX^1SIGMA^+ states of CO at 100eV impact energy using electron energy-loss spectroscopy.