As has been previously proposed, a minimal modification of the standard SU(
3) x SU(2) x U(1) theory provides a viable dark matter candidate. Such a pa
rticle, a scalar gauge singlet, is naturally self-interacting - making it o
f particular interest given recent developments in astrophysics. We review
this dark matter candidate, with reference to the parameter ranges currentl
y under discussion. (C) 2001 Elsevier Science B.V. All rights reserved.