Between 1973 and 1991, 12 patients with mycotic aneurysm of the abdominal aorta underwent operation. There were four elective and eight emergency procedures. In situ reconstruction was performed in six patients and extra-anatomic reconstruction with axillobifemoral bypass grafting in six. The hospital mortality rate was 25% (three patients) and another three died during the follow-up period of mean 5.5 years. Descending aorta-bifemoral bypass was performed in two patients without signs of chronic local infection 1 and 2 years after previous axillobifemoral bypass. Late complications were peripheral embolization in one patient after in situ reconstruction and a total of five thromboses of the axillofemoral bypass in three patients. Extra-anatomic bypass grafting remains the method of choice for the majority of patients with mycotic aneurysm of the abdominal aorta. In situ reconstruction seems to be an appropriate procedure for a highly selected group of patients.