  We consider a singlino dominated neutralino in supersymmetric models with an
extra U(1). In case both the $\mu$ term and also the $Z^\prime$ mass are
generated by the vacuum expectation value of the scalar component of the same
singlet chiral superfield, generically the lightest neutralino is not expected
to be dominated by the singlino. However, if the gaugino corresponding to the
extra U(1) is sufficiently heavy, the lightest neutralino can be dominated by
the singlino and still satisfy the constraints resulting from the $Z^\prime$
phenomenology. We assume a supersymmetry breaking scenario in which the extra
U(1) gaugino can be much heavier than other gauginos. In that framework we show
that the singlino dominated lightest neutralino may be a good candidate for
dark matter in a parameter space where various phenomenological constraints are
satisfied.
