To study the nature of low-z Ly{alpha} absorbers in the spectra of QSOs, we have obtained high signal-to-noise ratio (S/N) UV spectra of H1821+643 (z_em_=0.297) and PG 1116+215 (z_em_=0.177) with the Goddard High-Resolution Spectrograph on the Hubble Space Telescope.