Adenovirus (ADV) is a recognized cause of severe disease among immunocompromised patients. We report a previously healthy 39-year-old female, admitted with influenza pneumonia and evolving with lung hemorrhage and acute renal failure requiring mechanical ventilation and hemodialysis. She received high corticosteroid doses due to an initial suspicion of alveolar hemorrhage. Lymphopenia already present before steroid use (567/μL), was maintained during the whole hospital stay (mean 782/μL). From the second week of admission she presented a high-volume diarrhea (mean 2.5 L/day) associated to intermittent bloody stools. An ulcerative enterocolitis was confirmed by CT images and colonoscopy. ADV was detected in a colonic tissue sample by real time PCR but not by a commercial filmarray test. Cidofovir-probenecid and racecadotril therapy were indicated without changing the clinical course of diarrhea and the patient finally died.