  The Be II 3131 A doublet has been observed in the solar-type stars 16 Cyg A &
B and in the late G-type star rho 1 Cnc, to derive their beryllium abundances.
16 Cyg A & B show similar (solar) beryllium abundances while 16 Cyg B, which
has been proposed to have a planetary companion of ~2 M_Jup, is known to be
depleted in lithium by a factor larger than 6 with respect to 16 Cyg A.
Differences in their rotational histories which could induce different rates of
internal mixing of material, and the ingestion of a similar planet by 16 Cyg A
are discussed as potential explanations. The existence of two other solar-type
stars which are candidates to harbour planetary-mass companions and which show
lithium and beryllium abundances close to those of 16 Cyg A, requires a more
detailed inspection of the peculiarities of the 16 Cyg system.
  For rho 1 Cnc, which is the coolest known object candidate to harbour a
planetary-mass companion (M > 0.85 M_Jup), we establish a precise upper limit
for its beryllium abundance, showing a strong Be depletion which constrains the
available mixing mechanisms. Observations of similar stars without companions
are required to asses the potential effects of the planetary companion on the
observed depletion. It has been recently claimed that rho 1 Cnc appears to be a
subgiant. If this were the case, the observed strong Li and Be depletions could
be explained by a dilution process taking place during its post-main sequence
evolution.
