Introduction: Severe back pain caused by a thrombosed and ruptured aortic abdominal aneurysm can imitate a lumbar disc herniation. Case presentation: We present the case of a 72-year-old dia-betic patient with chronic atrial fibrillation, who had been experiencing highintensity low back pain and claudication in the last year prior to his presentation. After experiencing a minor trauma, a lumbar MRI examination was performed, which revealed a retroperitoneal tumoral mass compressing and eroding the L2–L4 vertebral bodies. Computed tomography angiography showed an infrarenal aortic aneurysm (3.374 Å~ 3.765 cm) which appeared to have ruptured and thrombosed. The question arising was when did the rupture occur, how massive was the damage, and how suitable for reconstruction was the aortic wall below the origin of the renal arteries. An open repair was scheduled and performed. The intraoperative finding was ruptured aneurysm of the thrombosed infra-abdominal aorta. The thrombosis extended along the common iliac and external iliac branches. We performed an aortobifemoral bypass using a 16 Å~ 8 mm Dacron graft, clamping the aorta above the origin of the renal arteries. Conclusion: The unintentional diagnosis, due to a minor fall, was overall a fortunate event for this patient. Aortic aneurysms may present with lumbar pain that can be mistakenly interpreted as a spinal issue.