BACKGROUND Acute aortic insufficiency can be secondary to multiple conditions, including infective endocarditis, aortic root pathologies (eg, dissection, aortitis), or traumatic injury. Aortitis involves a broad spectrum of disorders characterized by inflammatory changes in the aortic wall. This pathology can be subsequently classified depending on its etiology into inflammatory and infectious causes. Large-vessel vasculitis (giant-cell arteritis, Takayasu arteritis, and IgG4-related vasculitis) is the most common non-infectious causes of aortitis. Giant-cell aortitis usually lacks the classic clinical findings of giant-cell arteritis such as headache, visual symptoms, or jaw claudication, which can be a diagnostic challenge. However, clinicians should have a high index of suspicion, since this pathology can evolve into potentially life-threatening conditions, including aortic aneurysm, aortic wall rupture, and aortic acute dissection. CASE REPORT We present a case of a 76-year-old woman who presented to the Emergency Department (ED) with shortness of breath associated with orthopnea, paroxysmal nocturnal dyspnea, and mild productive cough with white sputum. A transthoracic echocardiogram demonstrated reduced left ventricular ejection fraction, dilated left ventricle, and severe aortic insufficiency. Cardiac catheterization revealed mild non-obstructive coronary arteries and severe aortic regurgitation. The surgical pathology report of the portion of the aorta was consistent with giant-cell aortitis. CONCLUSIONS In this article, we present a case of giant-cell aortitis as an unusual etiology of acute aortic insufficiency, which is most probably under-detected in clinical practice. In addition to describing the case, we aim to highlight the importance of proper ascending aorta evaluation in patients presenting with new-onset aortic regurgitation and heart failure to prevent associated morbidity and mortality.