BACKGROUND: Aortic complications after intravesical Bacillus Calmette-Guérin (BCG) application are a rare complication of the treatment of non-muscle invasive bladder cancer. The aim of this systematic review was to perform a descriptive analysis of previously published studies and to discuss the particular challenges of diagnosis and treatment of this rare complication. MATERIAL AND METHODS: A literature search was performed in PubMed (1949-2021) and Web of Science (1900-2021) using the search terms `mycobacterium` OR `bovis` OR `BCG` AND `aorta` OR `aneurysm`. In a staged review process, publications with the following inclusion criteria were included in data analysis: original paper, full-text availability in English or German and aortic complication after intravesical BCG instillation. We focused on the analysis of BCG-specific medical history data as well as treatment strategies in relation to patient outcome and the occurrence of graft infections during follow-up. RESULTS: A total of 60 individual cases were described in 55 published articles. BCG-induced mycotic aortic aneurysms can occur in all segments of the thoracoabdominal aorta, but the infrarenal aortic segment was most commonly affected (65% of cases). The most common configuration was saccular outpouchings (65%). Concomitant infections in other tissues were typical (65%). Patients with mycotic aneurysm presented with or without consecutive aortic rupture in 28% and 63%, respectively. Diagnosis was based on a combination of pathological and microbiological examinations. A common treatment algorithm was surgical infection treatment (85%) and antitubercular therapy (83%). Performed simultaneously, they resulted in a long-term survival of 81%. Graft infection after initial aortic repair with alloplastic material (n = 40) developed in ten patients (25%) during follow-up. DISCUSSION: Diagnosis of mycotic aneurysms or vascular complications after intravesical BCG application is exceptionally challenging and a high level of suspicion is required. Diagnosis is based on obtaining sample material of affected regions and the combination of patient's history, clinical presentation and pathological or microbiological examinations. Currently, no consensus guideline for optimal medical treatment options of aortic complications secondary to BCG instillation exists. The combination of surgical treatment and supportive antitubercular therapy seems to achieve the best results. Since the risk of prosthetic infection after the use of alloplastic materials remains high (25%), we strongly suggest evaluating autologous or allogenic aortic replacement during initial aortic repair.