Delirious mania is a severe but under-recognized neuropsychiatric syndrome characterized by the rapid onset of delirium, mania, and psychosis, not associated with a prior toxicity, physical illness, or mental disorder. Catatonia is often a prominent feature of the syndrome. While initially believed to be rare, recent reports suggest that delirious mania may constitute up to 15% of all acute mania cases. When delirious mania is unrecognized or improperly treated, it can progress rapidly in severity and can become life-threatening. This article reviews the pathophysiology, diagnosis, and treatment of delirious mania and includes a detailed case report. Delirious mania is robustly responsive to high-dose lorazepam or electroconvulsive therapy (ECT); thus, early recognition and definitive treatment can be life-saving.