Itraconazole is a synthetic antifungal agent approved in the USA for the treatment of onychomycosis and serious systemic fungal infections. Animal and clinical pharmacology studies suggest negative inotropic effects with itraconazole. Data from the US Food and Drug Administration's Adverse Event Reporting System suggest that use of itraconazole is associated with congestive heart failure. We summarise the details of 58 cases suggestive of congestive heart failure in association with the use of itraconazole. Labelling of itraconazole has been changed to alert physicians to this new finding.