Abstract The spin excitations in the model Heisenberg ferromagnets EuS and Pd 2MnSn have been investigated below T c using polarized-neutron scattering. In EuS the spin waves with transverse polarization with respect to q (δ S ⊥ q ) renormalize near T C as expected according to dynamical scaling theory, and the excitations have a gap with Δ ⋍ 0.040 meV. In contrast, the longitudinal spin waves (δ Sq ) are possibly damped. These observations are clearly related to the strong dipolar anisotropy that has already been observed above T C. Similar investigations in Pd 2MnSn show, that the spin waves are independent of the polarization within the q-range investigated. This result confirms that the dipolar interactions in Pd 2MnSn are indeed small.