In the last few decades, pellet injection has become an important tool of discharge operation and control. In ITER, plasma fuelling and edge localized mode (ELM) pacemaking will rely mainly on pellet injection (other applications will be impurity injection for diagnostic purposes and disruption mitigation). This paper describes our present understanding of the physics of ablation and ∇B-induced displacement of the pellet material, presents last experimental results on discharge fuelling and ELM pacemaking by pellet injection and discusses—on the basis of simulation results—how the experiments performed in present day machines can be extrapolated to ITER.