  Separative von Neumann regular rings exist in abundance. For example, all
regular self-injective rings, unit regular rings, regular rings with a
polynomial identity are separative. It remains open whether there exists a
non-separative regular ring. In this note, we study a variety of conditions
under which a von Neumann regular ring is separative. We show that a von
Neumann regular ring $R$ is separative under anyone of the following cases:
{\it (1)} $R$ is CS; {\it (2)} $R$ is pseudo injective (auto-injective); {\it
(3)} $R$ satisfies the closure extension property: the essential closures in
$R$ of two isomorphic right ideals are themselves isomorphic.
  We also give another characterization of a regular perspective ring
(Proposition 3.3)
