  We present numerical simulations of the runaway fractions expected amongst O
and Wolf-Rayet star populations resulting from stars ejected from binaries by
the supernova of the companion. Observationally the runaway fraction for both
types of star is similar, prompting the explanation that close dynamical
interactions are the main cause of these high-velocity stars. We show that,
provided that the initial binary fraction is high, a scenario in which
two-thirds of massive runaways are from supernovae is consistent with these
observations. Our models also predict a low frequency of runaways with neutron
star companions and a very low fraction of observable Wolf-Rayet--compact
companion systems.
