The clinical features and changes in blood and rumen fluid, and the results of therapy are described in 10 cows suffering from acute functional pyloric stenosis. The general condition of the cows was moderately to severely disturbed. The abdomen of most of them was distended on one or both sides and the rumen was excessively full. Defecation was reduced or absent. In most of them there was moderate or severe abomasal reflux-syndrome. Exploratory laparotomy or slaughter revealed a grossly distended abomasum which was filled with ingesta but not displaced. The omasum, reticulum and rumen of most of the cows were dilated secondarily and filled with ingesta. Six of the cows were treated by the administration of a solution of sodium chloride, glucose and potassium chloride intravenously, and metoclopramide intramuscularly. Five cows recovered within a short time, general condition, appetite and defecation were again normal and the abomasal and ruminal function returned within three days.