This article compares the concepts, scopes of application and procedural regimes of war crimes and grave breaches, while considering what role remains for the latter in international criminal law. In addition to their original conception as international obligations to enact and enforce domestic crimes, grave breaches have taken on a new meaning as international crimes, similar to war crimes. Only in few regards does the scope of application of these new grave breaches surpass that of war crimes. The procedural regime of grave breaches differs in theory significantly from that of war crimes, though less so in practice. Although it is too early to discount grave breaches, they are likely to become confined to history.