  We report a high-resolution (R=3000-4000) spectroscopic observation of the DA
white dwarf G191-B2B in the extreme ultraviolet band 220-245 A. A low- density
ionised He component is clearly present along the line-of-sight, which if
completely interstellar implies a He ionisation fraction considerably higher
than is typical of the local interstellar medium. However, some of this
material may be associated with circumstellar gas, which has been detected by
analysis of the C IV absorption line doublet in an HST STIS spectrum. A stellar
atmosphere model assuming a uniform element distribution yields a best fit to
the data which includes a significant abundance of photospheric He. The
99-percent confidence contour for the fit parameters excludes solutions in
which photospheric He is absent, but this result needs to be tested using
models allowing abundance gradients.
