A theoretical analysis and interpretation of the reported UV absorption spectra of the anti and gauche conformers of n-tetrasilane is offered, based on the results of multistate complete active space second-order perturbation theory (MS-CASPT2) calculations for their low-energy valence electronic excited states. A generally contracted basis set of atomic natural orbitals (ANOs) and a ground-state geometry optimized at the second-order Moller-Plesset perturbation theory (MP2) level by use of Dunning's correlation-consistent triple-zeta basis set (cc-pVTZ) have been used. Six valence excited states are calculated for the anti conformer. In terms of natural orbitals they correspond to single-electron promotions from the sigma(1) highest occupied molecular orbital (HOMO) to four sigma* and two pi* valence orbitals. Eight valence excited states are computed for the gauche conformer. Six of these correlate with the states calculated for the anti conformer, while two are new and correspond to single-electron promotions from the sigma(2) HOMO-1 to the sigma(1)* and sigma(2)* valence orbitals. The interpretation of the UV absorption spectrum of n-tetrasilane in terms of the present calculations shows strong contributions from six valence states instead of four. The main contribution to the second band is from the gauche conformer and involves an excitation from the sigma(2) HOMO-1 orbital, which was previously not emphasized. The description of the conformational effects on the spectrum confirms the proposal that the energy of the electronic transitions has a weak dependence on the backbone dihedral angle, while the computed intensity is strongly affected by the conformation.