Pellet injection was investigated for its fuelling capability to high densitiesin ELMy H mode discharges at JET.Applying the high field side launch system, optimized refuelling scenarios weredeveloped on the basis of conventional discharge configurations with Ip = 2.5 MA,Bt = 2.4 T, averaged triangularity ⟨δ⟩≈0.34 and mainly neutralbeam heating at a level of approximately 17 MW.The accessible operational range was extended with respect togas puff refuelling by the use of pellet injection. For example, H mode conditions could be maintained at densities beyond the Greenwald level.Plasma energy confinement was observed to become density independent at highdensities.Deep pellet particle deposition made possible the uncoupling of edge and core density,allowing more peaked density profiles.When confinement deterioration due to pellet triggered MHD activity orparasitic pellet borne gas was avoided in appropriate pulse schedules, an enhanced particleinventory was achieved while maintaining the plasma pressure profile.In a technical assessment it was found that there is still room forfurther enhancement of the injection scenario by improved adaptation to highdensity plasma operation.