  We explore gauge coupling unification and dark matter in high scale
supersymmetry where the scale of supersymmetry breaking is much above the weak
scale. The gauge couplings unify as precisely as in low energy supersymmetry if
the higgsinos, whose mass does not break supersymmetry, are much lighter than
those obtaining masses from supersymmetry breaking. The dark matter of the
universe can then be explained by the neutral higgsino or the gravitino. High
scale supersymmetry with light higgsinos requires a large Higgs mixing
parameter for electroweak symmetry breaking to take place. It is thus naturally
realized in models where superparticle masses are generated at loop level while
the Higgs mixing parameter is induced at tree level, like in anomaly and gauge
mediation of supersymmetry breaking.
