  The Lax pair of the Ruijsenaars-Schneider model with interaction potential of
trigonometric type based on Dn Lie algebra is presented. We give a general form
for the Lax pair and prove partial results for small n. Liouville integrability
of the corresponding system follows a series of involutive Hamiltonians
generated by the characteristic polynomial of the Lax matrix. The rational case
appears as a natural degeneration and the nonrelativistic limit exactly leads
to the well-known Calogero-Moser system associated with Dn Lie algebra.
