Brentuximab vedotin (BV), an antibody drug conjugate against CD30, has been increasingly used in clinical practice, and the less common adverse events associated to the drug are not well described. Also, opportunistic infections have been reported, and data on immune reconstitution after use of BV are lacking. The authors describe a case of a 45-year-old man with Hodgkin lymphoma receiving BV as a consolidation therapy after autologous hematopoietic stem cell transplant. After nine months of consolidation with BV, the patient developed a respiratory disorder characterized by fever, chills, dyspnea, and hypoxemia, and pneumonia by Pneumocystis jirovecii (PJ) was confirmed by bronchoscopy with bronchoalveolar lavage. In spite of the fact that there are no specific recommendations about infectious prophylaxis in patients using the drug, we would like to draw the attention of professionals who use the medication in relation to the risk of opportunistic infections, such as pneumonia by PJ.