This study was aimed at evaluating the capabilities of Doppler US in the quantitative study of portal blood flow after glucagon administration in normal subjects. While its role in the qualitative study of portal hemodynamics is well known, it remains questionable whether Doppler US may be a valuable tool for the quantitative study of portal blood velocity. This may be solved by introducing, on a routine basis, meal tests which may provide a relative evaluation of the data. To date, these tests were based on the evaluation of blood flow velocity before and after a complete meal. For a more reliable test, we suggest that the meal be substituted with the i.v. administration of glucagon, which is known to play a major role in splanchnic hemodynamics during digestion. We examined 30 healthy volunteers and showed the possibility of a statistically significant evaluation of portal blood flow velocity before and after glucagon administration. After glucagon administration, blood flow velocity increased by 31.3% in 10 minutes, on the average, in all the healthy subjects.