A new method for multiple, quantitative estimation of regional splanchnic blood flow is presented which overcomes all the limitations of the radionuclide microsphere technique. By direct comparison of two methods, i.e., simultaneous blood flow measurement with radionuclide-labeled and colored microspheres, it was shown that the quality of flow measure was quite similar. Simultaneous measurement using paired radionuclide-labeled microspheres yielded an excellent correlation between both values of r = 0.997, a variability of 4.58 +/- 3.84% and a SEE-value of 0.167 ml/g/min. The colored microsphere technique produced corresponding values with r = 0.998, a variability of 5.94 +/- 7.80% and a SEE-value of 0.212 ml/g/min (n.s.). This is also shown for five different abdominal organs and tissues with quite different flow rates under normal physiological conditions. Thus, the colored microsphere technique is a suitable experimental method for making multiple and quantitative measures of the nutritive blood flow through splanchnic organs and tissues and yields values of arterial blood inflow into the liver and into the circulatory bed which is drained by the portal vein.