Abstract. Moving ice imposes large forces on offshore structures in the Arctic, and those forces usually govern the design. Ice is one of the most brittle substances there is, with a fracture toughness 1/1000 th that of steel. Fracture dominates almost all interactions between structures and ice, and accounts for the pronounced size effect that is observed. This talk discusses the research that has been carried out in what is still a controversial and incomplete subject. Design cannot wait until all the theory is fully understood, and the work that has been done to try to bridge the gap between fracture mechanics and the needs of designers will be discussed, together with the role of field measurements and model tests. The field remains wide open for further research.