Determination of flow through splenorenal shunts performed for portal hypertension was tried in 7 patients using a dye dilution technique. Varying shunt flows were obtained. The results of the flow determinations were compared with the findings at arteriography and the cause of the varying flows could be revealed. Retrograde flow through the left ovarian vein leading to incomplete mixing was the most common source of error. The employed dye dilution techniques lends itself to shunt flow determination only if sources of error can be ruled out by arteriography.