The products of photo-isomerization when excited directly up to the two-photon-allowed (1)A(g)(-) excited state of alltrans and five cis isomers of retinal were determined. The composition of the isomers at the photo-stationary state was drastically changed as compared to one-photon excitation. The production of the 13-cis isomer was selectively increased, and the production of the dicis isomers was observed in the case of a direct excitation upon the 3(1)A(g)(-) state, although they were hard to be produced by one-photon excitation in n-hexane solution. These results clearly evidenced that there exist isomerization pathways via two-photon-allowed excited states. (C) 2003 Elsevier Science B.V. All rights reserved.