In the present contribution we performed ab initio Møller-Plesset perturbation theory to fourth order (MP4) and coupled-cluster CCSD(T) calculations in the framework of the supermolecule approach on the vertical excitation spectra of the weakly bound van der Waals CO-He molecule in its "near T-shaped" most stable ground state structure. They indicate that the excited Co(a3II)-He(1S) triplet interaction has Re = 3.47 Å, De = 22.87 cm-1 and Do = 6.07 cm-1 for CO(3A′)-He(1S), and Re = 3.41 Å, De = 24.90 cm-1 and Do = 7.46cm-1 for the CO(3A″)-He(1S) electronic state. They also indicate an excited CO(A1II)-He(1S) singlet interaction with Re = 3.49 Å, De = 20.92 cm-1 and Do = 5.05 cm-1 for CO(1A′)-He(1S), and Re = 3.37 Å, De = 27.21 cm-1 and Do = 8.24 cm-1 for the CO(1A″)-He(1S) state. © 2001 Elsevier Science B.V.