States enjoy the right to unilaterally denounce sovereign debt that is odious, illegal and illegitimate under strict circumstances. This entitlement does not exist where the debt(s) was/were incurred lawfully. A particular form of denunciation is sovereign insolvency, whose unilateral manifestation, is treated in practice by similar principles and responses as those apply mutatis mutandis to other forms of debt management. This chapter identifies, in addition to insolvency, five forms of unilateral debt denunciation that arise from the limited practice of states, which are moreover consistent with general international law. These are: (a) repudiation or non-enforcement of arbitral awards on public policy grounds; (b) denunciation on grounds of executive necessity and/or the right to fiscal/tax sovereignty; (c) direct unilateral repudiation on the basis of reports by national debt audit committees; (d) repudiation of contracts when creditor/investor violates human rights and of unconscionable concession contracts; (e) re-negotiation of bilateral investment treaties and concessions.