Various electronically excited states of pyrrole have been studied by ab initio SCF and CI calculations including rr -. n* and zr -Rydberg excitatiorz Optically allowed vaIenc= type transitions are found at energies higher Thea 65 eV_ whereas all the Iower singIet states are of Rydberg type. In addition to the experimental.& known tsiplet states at 4.23 and 5.10 eV, scverzd new triplet transitiors with energjes from 5.X to 7.10 eV are predicted In most cases good agieement with experimental data is found. f . Iutroduction Optical absorption measurements In the W region of the mdecule pyrroIe have been performed for more than fifty years [l-7]. In 1971, *he photoelectron spectrum was measured by Derrick et aI_ [S] _ These authors revised the assignments of MuIIen and Orfoff [6] and explained most of the absorption bands by three Rydberg series, ohe of which Ieads to the second ionization potential Bavia et aI. [7], however, found no evidence for this latter Rydberg series from their absorption measurements. Recently, electron impact experiments have been performed in order to study triplet excitations and electric dipole forbidden transitions 19, lo] _ Theoretical studies of the excited states of pyrrcle up to now have been based on semiempirical methods alone. They couId not give a consistent expIauation of the spectrum [ l l -16]_ Non-empirical SCF calculations were restricted to the study of the electronic structure of the pound state [17--191 or to the validity of the 0, ir separation [20]_ The recent progress in CI techniques deveIoped in our Iaboratory aIIows for an efficient handling of large basis sets and large configuration spaces. Thus moie-c&s of this size can hopefully be studied routinely by ab initio Cl techniques without o, z separation. The purpose of this work is to examine the experimental