BSTRACTWe reveal that in a prototypical bcc high-entropy alloy NbMoTaW chemical interactions are long ranged and highly frustrated. We show that this is the reason that bcc solid solutions in NbMoTaW can persist to low temperatures. The ab initio-computed long-ranged interactions strongly impact characteristic thermodynamic properties and ordering temperatures. This highlights the genuine importance of taking long-ranged chemical interactions into account for accurate theoretical predictions of high-entropy alloy properties.