This article examines the grounds upon which Australian courts intervene in the enforcement of letters of credit and performance guarantees by granting injunctions. A review of cases indicates that whilst an applicant may raise fraudulent conduct and unconscionable conduct as grounds for interlocutory relief restraining a beneficiary's call under a letter of credit or performance guarantee, an additional reason known as a negative stipulation in the contract may also be available for restraining a beneficiary calling under a performance guarantee. This article concludes with a policy perspective of fraud and unconscionability as established grounds upon which injunctions are granted.