Adenoviral infections of immunocompetent patients usually present as self-limiting pharyngitis, gastroenteritis, urocystitis, or conjunctivitis. In immunosuppressed patients, development of the illness can be severe, even life-threatening or fatal, and therapeutical intervention is difficult. Previous case reports of adenoviral infections after kidney transplantation have described a symptomatology of hemorrhagic cystitis, fever, renal dysfunction, and rarely fatal systemic dissemination. Here we report on a 46-year-old female renal transplant recipient suffering from adenoviral serotype 35 nephritis of the donor organ 29 days after transplantation. In this case, the main symptoms of the adenoviral infection were high fever and progressive renal failure of the transplanted organ. At the peak of the clinical symptoms, owing to histological and immunohistochemical evaluations of a kidney biopsy, we were able to establish the diagnosis in time so that adequate therapy could be employed. Immunosuppression was reduced and modified, and a self-limiting course of the infection was observed, followed by significant improvement of graft function. Subsequent to histological diagnosis, adenoviral particles were isolated from urine and identified as adenovirus serotype 35. Adenoviral nephritis of the transplanted organ should be considered in the differential diagnosis of persistent anuria after kidney transplantation. Our case highlights the importance of applying all possible diagnostic techniques, including histological evaluation of renal biopsies.