Strengthening of flux-line pinning in high- T c compounds by ferromagnetic particles created by implantation of iron ions has been observed. Measurements were carried out at single crystals of Bi 2Sr 2CaCu 2O 8 and thin films of YBa 2Cu 3O 7 by means of field-modulated microwave absorption technique. In case of YBa 2Cu 3O 7, experiments were performed on composite structure consisting of the superconducting film and non-conducting SiO 2 film containing magnetic particles.