The influence of carbohydrate, carbohydrate-fatty and protein test breakfasts on the rate of gastric stump evacuation was studied in 62 patients with dumping syndrome of mild and moderate severity, using the x-ray method developed by the authors. It has been established that in patients with dumping syndrome carbohydrate and carbohydrate-fatty food is most quickly evacuated from the gastric stump. Doubled amount of fat in the carbohydrate-fatty breakfast (up to 40 g) induced no significant deceleration in the gastric stump evacuation, moreover, in some cases its evacuatory function was accelerated. Intake of mineral water before breakfast did not noticeably influence the rate of gastric stump evacuation after carbohydrate and carbohydrate-fatty breakfasts, and significantly decelerates the gastric stump evacuation after protein breakfast.