Abdominal aortic aneurysm with spontaneous aorto-left renal vein fistula is a rare but well-described clinical entity usually with abdominal pain, hematuria, and a nonfunctioning left kidney. This report describes a 44-year-old man with left-sided groin pain and varicocele who was treated with conservative measures only. The diagnosis was eventually made when he returned with microscopic hematuria, elevated serum creatinine level, and nonfunction of the left kidney; computed tomography scan demonstrated a 6-cm abdominal aortic aneurysm, a retroaortic left renal vein, and an enlargement of the left kidney. This patient represents the youngest to be reported with aorto-left renal vein fistula and the second case with a left-sided varicocele.