SummaryIn 20 people picked up from a radiological out patients department where they had be sent for radioscopy of the lungs, a radiography of the heart was taken just before the intake of one liter of water, another picture was taken in the same conditions 40 minutes later.The time of exposure was sufficient to include a total systolic and diastolic period. For that reason the obtained shadow was that of the heart during the diastolic repletion of the heart cavities.By measuring three diameters of the heart on each of the pictures before and after ingestion of water, it was observed that the 3 diameters of the heart increased by drinking water of 5,31 %, 4,84 % and 4,11 % as an average.An increase of 5 % of the diameters would indicate an increase of the cardiac volume of 15 % if admitted that the heart was spheric. When the increase of the 3 diameters was maximum (about 10 %) the increase of the total volume would be 33 %.Although this method does not allow an exact measure of the volume increase after intake of water, these observations completly agree with those of Govaerts and Lequime, on the cardiac output after intake of water.