We have used the HST Planetary Camera to search for companions to a sa
mple of low-mass (M(nu)>11.5) members of the Hyades cluster. Our obser
vations, which extend in sensitivity beyond the hydrogen-burning limit
, detect 5 companions amongst the 21 targets. One binary system appear
s to Lie 70% beyond the Hyades, so the observed binary fraction is 20%
+/-10%. If the distribution of orbital parameters is similar to that o
f higher mass stars, this implies an overall binary fraction of 27%+/-
16%. Our result for the Hyades is in good agreement with analysis of t
he 5.3 pc nearby star sample, but is significantly lower than the bina
ry fractions observed amongst similar to 1M(circle dot) main-sequence
stars (similar to 60%) and T Tauri stars (>70%). (C) 1995 American Ast
ronomical Society.