  The Generalized Uncertainty Principle and the related minimum length are
normally considered in non-relativistic Quantum Mechanics. Extending it to
relativistic theories is important for having a Lorentz invariant minimum
length and for testing the modified Heisenberg principle at high energies.In
this paper, we formulate a relativistic Generalized Uncertainty Principle. We
then use this to write the modified Klein-Gordon, Schr\"odinger and Dirac
equations, and compute quantum gravity corrections to the relativistic hydrogen
atom, particle in a box, and the linear harmonic oscillator.
