Perioperative shoulder infections involving Propionibacterium acnes can be difficult to identify in a patient who presents with little more than pain and stiffness in the postoperative period. Although indolent in its growth and presentation, infection of the shoulder with P acnes can have devastating effects, including failure of the surgical intervention. This article reviews the importance of a comprehensive physical, radiologic, and laboratory evaluation, and discusses appropriate preventive and treatment strategies for P acnes infections of the shoulder.