Introduction: Wegener's granulomatosis (WG) is a rare long-term systemic disorder that involves the formation of granulomas and inflammation of blood vessels. Aim: of this study was to present a case of (WG) that was diagnosed with kidney biopsy while the lung infiltrates were not reachable. Materials and methods: 57-year-old male patient admitted for invasive diagnostics due to lung infiltrates. Results: The patient had positive C-ANCA on bloodwork, CT scan showing multiple bilateral lung infiltrates and an inconclusive result from a nasal mucosa biopsy. The lung infiltrates being difficult to reach for biopsy and having confirmed kidney involvement with high creatinine and albuminuria enabled us to do kidney biopsy. The biopsy showed a vasculitis with positive C-ANCA confirming (WG). A high dose of Methylprednisolone (500mg for 3day, then 250 for 3 day and finally 125mg for 3 days) A cyclophosphamide and maintenance dose steroids therapy was initiated by a consulting rheumatologist after discharge. A complete remission of the lung involvement was seen on a CT 2 months after. Discussion: The least invasive site for biopsy being the nasal mucosa is always the best site for biopsy. Having received an inconclusive result leaves the kidney and the lung as secondary options. In our case the kidney was considered due to a better possible yield of viable material Conclusion: Present kidney involvement is always a site for biopsy with a high yield for confirming (WG) despite the risk of bleeding complications who were absent in our case.