OBJECTIVE This study was undertaken to illustrate the safety of in situ reconstruction of septic aortic pseudoaneurysm (SAP) secondary to microbial aortitis, with or without long-term antibiotic treatment. METHODS Data for patients with SAP (11 abdominal, 4 thoracic) operated on between 1993 and 1999 were reviewed. Computed tomography and aortography showed septic pseudoaneurysm in all patients before surgery. After diagnosis of SAP, all patients underwent aneurysm resection and extensive debridement, with in situ prosthetic grafting or patch repair angioplasty. The graft in 10 of the 11 patients with abdominal SAP was also wrapped with an omental pedicle. In vitro active parenteral antibiotic therapy was prescribed for all patients for at least 2 to 8 weeks after surgery. RESULTS All 15 patients had positive preoperative blood cultures or intraoperative tissue cultures for Salmonella spp (n = 12), viridans Streptococcus (n = 1), group G Streptococcus (n = 1), or Streptococcus pneumoniae (n = 1). There were two perioperative deaths (13.3%), one 6 days after surgery and the other 19 days after surgery, and two late deaths, at 8 and 10 months after surgery, neither of which was related to aortic repair. One patient was unavailable for follow-up. The other 10 patients have been regularly followed up with abdominal ultrasound or computed tomography (mean, 84 months; range, 47-118 months). To date, there has been no graft infection, thrombosis, false aneurysm, or subsequent aortic surgery in these 10 patients. CONCLUSION SAP due to Salmonella and streptococcal microbial aortitis can be successfully treated with resection of the aneurysm and extensive debridement, followed by in situ prosthetic graft interposition or patch repair aortoplasty. This is a safe and effective treatment that may result in complete remission of SAP. Postoperative parenteral antibiotic therapy should be continued for 2 to 8 weeks. Although usually recommended, lifelong suppressive antibiotic therapy appears to be nonessential with this approach.