  We show that the generalized holonomy groups of ungauged supergravity
theories with 8 real supercharges must be contained in SL(2-\nu,H)\ltimes{\nu
H^{2-\nu}}\subseteq SL(2,H), where SL(2,H) is the generalized structure group.
Here n=4\nu is the number of preserved supersymmetries, so the allowed values
are limited to n=0,4,8. In particular, solutions of ungauged supergravities in
four, five and six dimensions are examined and found to explicitly follow this
pattern. We also argue that the G-structure has to be a subgroup of this
generalized holonomy group, which may provide a possible classification for
supergravity vacua with respect to the number of supercharges.
