  We reanalyze the inference of the protosolar abundance of deuterium made by
Geiss (1993) from measurements of 3He/4He in the solar wind. We use an
evolutionary solar model with microscopic diffusion, constrained to fit the
present age, radius and luminosity, as well as the observed ratio of heavy
elements to hydrogen. The protosolar 2H/1H is obtained from the best fit of
3He/4He in the solar wind. Taking for the protosolar 3He/4He the value measured
in Jupiter by the Galileo probe (Niemann et al. 1996), we derive the protosolar
2H/1H=(3.01 +- 0.17) 10^{-5} ratio. Compared to the present interstellar medium
value (Linsky et al. 1993), this result is compatible with models of the
chemical evolution of the Galaxy in the solar neighborhood; it is also
marginally compatible with the Jovian 2H/1H=(5 +- 2) 10^{-5} ratio measured by
Galileo.
