Luis Gonzalez-Mestres Lorentz symmetry violation and high-energy cosmic rays (78K, PS) ABSTRACT. We discuss possible violations of Poincare's relativity principle at energy scales close to Planck scale and point out the potentialities of high-energy cosmic-ray physics to uncover these new phenomena. Talk given at TAUP 97 , Gran Sasso September 1997 . Author E-mail: lgonzalz@vxcern.cern.ch .