We report a case of adult respiratory distress syndrome (ARDS) associate to renal failure in a patient labeled of "round pneumonia" some weeks before. An open biopsy was made that only showed typical findings of ARDS. The patient was treated with corticosteroids and cyclophosphamide because of cANCA positivity. We discuss the utility of this determination in Wegener disease and we conclude that this determination should be made in this clinical setting and start immunosuppressive treatment when cANCA is positive.