  We discuss the bihamiltonian structure of the Metsaev-Tseytlin superstring in
AdS_5 x S**5. We explicitly write down the boost-invariant symplectic structure
for the superstring in AdS_5 x S**5 and explain its relation to the standard
(canonical) symplectic structure. We discuss the geometrical meaning of the
boost-invariant symplectic structure for the bosonic string.
