Mycotic aneurysm is a serious clinical condition with significant morbidity and mortality. Staphylococcus aureus and Salmonella species are the most common causative pathogens. Klebsiella pneumoniae was rarely reported as a possible pathogen causing mycotic aneurysm; therefore, we describe a K. pneumoniae-related fatal bacteremia mycotic aneurysm in a patient in spite of appropriate antimicrobial agents and surgical management.