Bacteria and myobacteria are important pulmonary pathogens in transplant recipients and are the focus of this article. Although considerable overlap exists, there are significant differences in the epidemiology and clinical presentation of these organisms in solid organ transplant (SOT) and hematopoietic stem cell transplant (HSCT) recipients. The first section of this article focuses on infections in SOT recipients (predominantly heart, liver, lung, and kidney transplant recipients), and the latter addresses these infections in HSCT recipients.