  We study the decays of ultraheavy (m_X \geq 10^{13}GeV) and quasistable
(lifetime \tau_X much larger than the age of the Universe t_0) particles as the
source of Ultra High Energy Cosmic Rays (UHE CR). These particles are assumed
to constitute a tiny fraction \xi_X of CDM in the Universe, with \xi_X being
the same in the halo of our Galaxy and in the intergalactic space. The
elementary-particle and cosmological scenarios for these particles are briefly
outlined. The UHE CR fluxes produced at the decays of X- particles are
calculated. The dominant contribution is given by fluxes of photons and
nucleons from the halo of our Galaxy and thus they do not exibit the GZK
cutoff. The extragalactic components of UHE CR are suppressed by the smaller
extragalactic density of X-particles and hence the cascade limit is relaxed. We
discuss the spectrum of produced Extensive Air Showers (EAS) and a signal from
Virgo cluster as signatures of this model.
