  We derive the leading order strangeness S=-2 baryon-baryon interactions in
chiral effective field theory. The potential consists of contact terms without
derivatives and of one-pseudoscalar-meson exchanges. The contact terms and the
couplings of the pseudoscalar mesons to the baryons are related via SU(3)
flavor symmetry to the S=-1 hyperon-nucleon channels. We show that the chiral
effective field theory predictions with natural values for the low-energy
constants agree with the experimental information in the S=-2 sector.
