Crohn disease (CD) may be associated with various extraintestinal manifestations, including, rarely, respiratory tract involvement. When necrobiotic pulmonary nodules are present, the differential diagnosis includes granulomatosis with polyangiitis (Wegener granulomatosis) (GPA). The respiratory tract manifestations of CD and GPA may mimic each other, complicating the diagnosis and suggesting the possible coexistence of these 2 conditions. The aim of this study was to describe the clinical, radiographic, and pathologic features of patients in whom CD and GPA coexist. We reviewed the teaching files of the authors and searched the Mayo Clinic medical records for coexistent inflammatory bowel diseases and antineutrophilic cytoplasmic antibodies (ANCA)-associated vasculitides. We reviewed in detail 97 patient charts and excluded cases of ulcerative colitis and those in whom only one of the diagnoses was present. Pulmonary and gastrointestinal biopsies were reviewed when available. We also searched the medical literature for previously published cases. We found 6 cases of coexistent CD and pulmonary GPA and 4 cases with extrapulmonary GPA; 3 cases (all with extrapulmonary GPA) have been published previously. The diagnosis of CD preceded that of GPA in 11 cases. Proteinase 3-ANCA was positive in 6 cases, negative in 2, and not reported in 5 cases. Myeloperoxidase-ANCA was negative in 6 cases and unavailable in the remainder of patients. Pathology revealed features diagnostic of GPA in all cases with necrotizing granulomatous inflammation and segmental vasculitis. Pulmonary findings in patients with CD or the presence of granulomatous colitis in patients with GPA should prompt the inclusion in the differential diagnosis of a possible coexistence of CD and GPA.