  Under the hypotheses of smoothness of the interactions in the coupling
constant, locality, Poincare invariance, Lorentz covariance, and the
preservation of the number of derivatives on each field in the Lagrangian of
the interacting theory (the same number of derivatives like in the free
Lagrangian), we prove that in D=11 there are no cross-interactions between the
graviton and the massless gravitino and also no self-interactions in the
Rarita-Schwinger sector. A comparison with the case D=4 is briefly discussed.
