Fulminant cases of Wegener’s granulomatosis (WG) with severe lung and kidney dysfunction may resemble pneumonia with sepsis and multiorgan dysfunction. Increased serum levels of antineutrophyl citoplasmic autoantibodies (c-ANCA) and proteinase 3 antibodies (PR3) confirm the correct diagnosis and are essential to start early immunosupressive treatment to improve the outcome. With the emphasis on diagnostic dilemmas, we present a 61-year old patient with fulminant WG, resembling pneumonia with sepsis and multiorgan dysfunction. After antibiotics and supportive measures increased serum levels of c-ANCA and PR3 confirmed the suspicion of WG and adequate immunosupressive treatment improved the patient’s condition. We concluded that it is important to include vasculitis in the differential diagnosis of unexplained multiorgan dysfunction, because only early adequate immunosuppressive therapy in combination with other resuscitation measures improves survival.