The interpretation of spectrum (7.5-13.5 nm) of an uranium plasma produced by laser impact on a target (metal or diluted compound) has allowed to identify six resonance lines of U XIII; they are superimposed to a continuum centered near 9.5 nm which is attributed to the bulk of n = 5, Dn = 0 transitions emitted by other uranium ions. The estimated error for the energy levels is about 300 cm^-1. Their interpretation is based on ab initio evaluations by the Dirac-Fock method (84.6).