  We suggest that the highest energy $ \gsim 10^{20} eV$ cosmic ray primaries
may be relativistic magnetic monopoles. Motivations for this hypothesis are
that conventional primaries are problematic, while monopoles are naturally
accelerated to $E \sim 10^{20} eV$ by galactic magnetic fields. By matching the
cosmic monopole production mechanism to the observed highest energy cosmic ray
flux we estimate the monopole mass to be $\sim 10^{10\pm1} GeV$.
