A modification of the vapour containment technique has enabled the X-u.v. absorption spectrum of Rb I vapour to be recorded at higher vapour densities than previously attainable. Twentyseven new transitions have been detected. These include a group of resonances extending up to 5 eV above the 3d thresholds and absorption lines attributed to excitation of the 3p subshell. The analysis of Mansfield & Connerade (1975 a) is extended in the light of the new data and of further comparisons with Hartree-Fock calculations.