We report three cases of ruptured mycotic thoracoabdominal aortic aneurysms (TAAAS) and a review of the literature. Escherichia coli and Streptococcus pneumoniae (2 patients) were the responsible organisms. Surgical management consisted of wide debridement of necrotic tissue and in situ repair with a Dacron graft. Antibiotics were administered intravenously in the hospital and continued orally after discharge for at least 6 weeks, until clinical and laboratory parameters were normalized. A review of the literature showed that Gram-negative microorganisms are found in 47% of mycotic TAAAs. A trend toward increased mortality for these organisms, compared with Gram-positive microorganisms, was observed (P =.09). Lifelong antimicrobial therapy is controversial. No difference in survival or recurrence rate was found between series advocating lifelong therapy and those suggesting prolonged (6 weeks to 12 months) therapy (median follow-up period, 18 and 19 months, respectively). In situ repair with synthetic material can be successful if prompt confirmation of infection is obtained, all possibly infected tissue is resected, and antibiotic therapy based on sensitivity data is administered for a prolonged period. A short-term survival rate as high as 82% can be expected with this strategy, but data on long-term survival rates are limited. Polytetrafluoroethylene-expanded grafts, homografts, and antibiotic-bonded grafts may offer advantages over Dacron grafts, but data are insufficient to draw conclusions. Careful long-term follow-up is an important element of the treatment of these patients. We suggest antibiotic treatment until biochemical parameters of inflammation (white cell count, erythrocyte sedimentation rate, or C-reactive protein) return to normal and a computerized tomography scan every 3 months for 1 year, then annually.