The diverse clinical presentations of mycotic aneurysms often present challenges in achieving early clinical diagnosis. Clinically, evident mycotic aneurysms frequently manifest at an advanced stage of progression or are concurrent with complications, such as rupture. In this report, we aim to discuss the mortality of a 68-year-old woman who had a rare ruptured mycotic aneurysm. Initially, the patient presented to the emergency department (ED) due to a sudden, sharp, stabbing sensation in the middle chest area, radiating to her back. An electrocardiogram (ECG) revealed sinus rhythm without ST-T changes. Chest X-ray (CXR) showed an enlarged aorta, which led to a diagnosis of suspected aortic dissection. During close monitoring in the Intensive Care Unit (ICU), the patient’s blood pressure dropped, and peripheral oxygen saturation was 70%. After urgent intubation and resuscitation, the patient was finally stable. Another CXR was performed and found massive pleural effusion; prompt pleural aspiration found the presence of blood. It was suspected that the suspected aortic dissection had ruptured causing massive left hemothorax. Computed tomographic angiography (CTA) was done but did not find evidence of aortic dissection. After a thorough discussion, the attending thoracic surgeon was to perform an exploratory thoracotomy. During preparation, the patient went into cardiac arrest. Adequate resuscitation was performed. Unfortunately, the patient was pronounced dead soon after. It was determined that mycotic aneurysm rupture was the underlying cause. This study showed a significant occurrence of aneurysm ruptures, underscoring the critical need for achieving early diagnosis of mycotic aneurysm.