A 74-year-old man, with a permanent pacemaker placed 2 years ago for high-grade atrioventricular block, was admitted for worsening fatigue, confusion, and thrombocytopenic purpura without fever. White blood cell count and C-reactive protein were elevated, and echocardiography revealed a 6 × 3-cm echogenic mass surrounding the pacemaker leads. Multiple blood cultures were performed, and only 1 bottle grew Propionibacterium acnes at 93 hours. The patient underwent surgery, and 16S rRNA gene polymerase chain reaction amplification confirmed the presence of P. acnes in the removed vegetation. Patients with late-onset, device-related endocarditis often present with vague symptoms and fever may be absent, obscuring the clinical diagnosis. Blood cultures and transesophageal echocardiography are key diagnostic tests. As a slow-growing, low virulent, and common human skin germ, P. acnes can be wrongly considered as a blood culture contaminant.