  We present an analysis of Hipparcos astrometric measurements of Upsilon
Andromedae, a nearby main-sequence star around which three planet candidates
have recently been discovered by means of radial-velocity measurements. The
stellar orbit associated with the outermost candidate has a period of 1269 +/-
9 days and a minimum semi-major axis of 0.6 milli-arc-sec (mas). Using the
Hipparcos data together with the spectroscopic elements we found a semi-major
axis of 1.4 +/- 0.6 mas. This implies a mass of 10.1 (+4.7, -4.6) Jupiter
masses for that planet of Upsilon Andromedae.
