We report on microwave measurements on DyBa2Cu3O7−δ monodomains grown by the top-seeded melt-textured technique. We measured the field increase of the surface resistance Rs(H) in the a–b plane at 48.3GHz. Measurements were performed at fixed temperatures in the range 70K–Tc with a static magnetic field μ0H<0.8T parallel to the c-axis. Low field steep increase of the dissipation, typical signature of the presence of weak links, is absent, thus indicating the single-domain behavior of the sample under study. The magnetic field dependence of Rs(H) is ascribed to the dissipation caused by vortex motion. The analysis of Xs(H) points to a free-flow regime, thus allowing to obtain the vortex viscosity as a function of temperature. We compare the results with those obtained on RE-BCO systems. In particular, we consider strongly pinned films of YBa2Cu3O7−δ with nanometric BaZrO3 inclusions.