AbstractA damping of spin waves is considered near the orientational phase transition (OPT) in the easy plane ferromagnet in an external magnetic field using the diagram technique for the Hubbard operators. It is shown that in the normal phase where uniaxial symmetry is not broken the damping takes place for nonzero temperature and increases with approaching the OPT point. In the broken symmetry phase the damping of spin waves takes place even atT= 0 and increases with going away from the OPT point.