Human bocavirus has been reported as an emerging pathogen of the lower respiratory tract, especially in younger children. Human bocavirus rarely causes an infection in adults; however, the significance of its discovery in the respiratory specimens of adult patients is still unclear. In previous reports, human bocavirus DNA was detected in patients with structural lung diseases or hematological malignancies. Herein, we will report on what we believe is the first case of pneumonia secondary to human bocavirus and two other pathogens in a patient with dermatomyositis.