  We present a new test of modified Newtonian dynamics (MOND) on galactic
scales, based on the escape speed in the solar neighbourhood. This test is
independent from other empirical successes of MOND at reproducing the
phenomenology of galactic rotation curves. The galactic escape speed in MOND is
entirely determined by the baryonic content of the Galaxy and the external
field in which it is embedded. We estimate that the external field in which the
Milky Way must be embedded to produce the observed local escape speed of 550
km/s is of the order of a_0/100, where a_0 is the dividing acceleration scale
below which gravity is boosted in MOND. This is compatible with the external
gravitational field actually acting on the Milky Way.
