Portosystemic shunts frequently develop in patients with cirrhosis. However, congenital splenorenal shunts are rare anomalies in people without portal hypertension. Here, we present a case of a venous shunt between the spleen and left renal vein in a 57-year-old man with no history of liver cirrhosis, portal hypertension, or hepatic encephalopathy. The abnormal vessel was identified on preoperative contrast-enhanced computed tomography performed for diagnosis of a left adrenal aldosterone-producing adenoma. The shunt was safely ligated during transperitoneal laparoscopic left adrenalectomy. Excessive bleeding due to accidental injury of the shunting vessel during the procedure is a likely complication. Careful review of preoperative computed tomography images and cautious management of this type of shunt, especially in cirrhotic patients, can prevent this serious complication.