  We constrain the hadronic R-parity violating couplings in extensions to the
minimal supersymmetric standard model. These interactions violate baryon and
lepton number, and allow the lightest superpartner (LSP) to decay into standard
model particles. The observed flux of cosmic ray antiprotons places a strong
bound on the lifetime of the LSP in models where the lifetime is longer than
the age of the universe. We exclude 10^-18<lambda''<10^-15 and
2x10^-18<lambda'<2x10^-15 except in the case of a top quark, where we can only
exclude 4x10^-19<lambda'<4x10^-16.
