  We construct stellar models of hadron stars and hybrid stars and calculate
the frequencies of their lowest radial mode of vibration. Chandrasekhar's
equation for radial oscillations is generalized for stars with internal
electric fields and earlier versions of that generalization are simplified. For
the hybrid stars a Gibbs construction is employed. It is found that the
softening of the equation of state associated with the presence of deconfined
quarks reduces the oscillation frequency. We show that a slight charge
inbalance should lead to increased maximum mass, decreased central density and
lower oscillation frequencies.
