Various electronically excited states of furan have been studied by ab initio CI calculations including π → π* and π → Rydberg transitions. Two low-lying triplet valence states are found in close agreement impact data, further triplets are predicted at energies above 7.2 eV. The latest experimental assignment of Rydberg states has been verified and addition two other series are predicted. Two singlet valence states are reported at 6.92 eV and 7.54 eV, the first of which has been calculated about 0.9 eV higher than the experimental maximum in absorption. A comparison of the results of furan and pyrrole shows that the triplet states found at about 5 eV in both molecules result from a π → π* excitation in furan and from a Rydberg state in pyrrole. There is a strong indication that the furan spectrum can be explained without regard to excitations out of n orbitals.