Portal hypertension is a result of chronic liver disease in the majority of cases. Rare, potentially curable causes of portal hypertension include vascular conditions such as hepatic or portal venous thrombosis and arterio-portal fistulas. We present the rare case of a spontaneous splenic arterio-venous fistula in a 40 year old multiparous woman. The young woman presented with massive diarrhea, ascites, abdominal pain, and an abdominal machinery type bruit and represents the second ever reported case with diarrhea as presenting symptom of splenic arterio-venous fistula. The diagnosis was confirmed by color Doppler ultrasound. Transfemoral aortography was performed to assess the possibility of catheter embolization. Surgical intervention was initially complicated by collateral arterial tributaries of the fistula and finally resulted in a dramatic recovery with persistent resolution of all symptoms. This case report demonstrates a curable form of portal hypertension that must be considered in acute onset portal hypertension in multiparous women and in the absence of liver disease. A machinery type bruit in the upper left abdominal quadrant represents an important and simple diagnostic symptom found by auscultation. Color Doppler ultrasound represents a non invasive, universally applicable and fast method of establishing the diagnosis. The literature and management of splenic arterio-venous fistulas are reviewed.