A 39-year-old patient with an 11-year history of kidney transplantation for severe amyloidosis was referred to the Centre d'Infectiologie Necker Pasteur for acute fever for 2 days. After 8 years of transplantation, he was treated for graft rejection by corticosteroids. Clinical course was uneventful, except for recurrent prostatitis. His current immunosuppressive regimen consisted of mycophenolate mofetil except for sore throat and rhinorrhea. Biological analyses showed an elevated C-reactive protein blood level (157 mg/L, normal <5 mg/L) but normal blood leukocytes and neutrophil counts. Blood lymphocyte count was low (0.94 G/L), with CD4+ T cells accounting for 39.5% of total lymphocytes (0.372 G/L). HIV serology was negative. Blood and urine cultures were sterile and initial chest radiograph was normal. Nonproductive cough without dyspnea or chest pain appeared on day 3 of hospitalization. Oxygen saturation in ambient air was 92%. Chest auscultation was normal. As the cough increased, a thoracic computed tomography (CT) scan was performed on day 6 and revealed bilateral ground glass infiltrates mainly located in subpleural and peripheral areas, associated with bilateral pleural effusion ( Figure 1 ). No mediastinal adenopathy was seen. Because of clinical and radiological presentation suggesting Pneumocystis jirovecii pneumonia, trimethoprim-sulfamethoxazole was initiated the same day. Nasopharyngeal aspirates were screened by direct immunofluorescence with specific monoclonal antibodies to RSV, influenza virus A and B, PIV, adenovirus, and hMPV (Argène, Verniolle, France) on day 7. Immunofluorescence was strongly positive for hMPV and negative for other viruses. Blood cultures and S. pneumoniae and L. pneumophila urinary antigen detections were negative. As Pneumocystis pneumonia was initially suspected, bronchoalveolar lavage (BAL) fluid analysis performed on day 11 demonstrated 450.10 3 cells/mL (macrophages 72%, neutrophils 17%, and lymphocytes 11%). Microbiological studies did not reveal any bacterial or fungal microorganisms. Gomori-Grocott staining for Pneumocystis jiroveci detection, indirect immunofluorescence, and polymerase chain reaction (PCR) for P. jiroveci were negative. hMPV was also detected in BAL fluid by direct immunofluorescence. As all microbiological investigations were negative except for hMPV, antibiotics were discontinued; respiratory symptoms spontaneously improved within 6 days. Thus, decreased immunosuppression or other medications such as ribavirin or intravenous immunoglobulin were not considered. The patient was discharged on day 14.