Summary: We introduce the notion of interval-valued \((\widetilde\theta,\widetilde\delta)\)-fuzzy KU-ideals of KU-algebras and some related properties are investigated. We prove that \(U(\widetilde\eta;\widetilde t)\) is a KU-ideal if and only if the interval-valued fuzzy subset \(\widetilde\eta\) is an interval-valued \((\widetilde\theta,\widetilde\delta)\)-fuzzy KU-ideal of a KU-algebra for \(\widetilde\theta\prec\widetilde t\preceq\widetilde\delta\).