We study D-branes on three-dimensional orbifold backgrounds that admit
topologically distinct resolutions differing by flop transitions. We
show that these distinct phases are part of the vacuum moduli space of
the super Yang-Mills gauge theory describing the D-brane dynamics, In
this way we establish that D-branes-like fundamental strings-allow fo
r physically smooth topology changing transitions. (C) 1998 Published
by Elsevier Science B.V.