The study compares the duodenal and jejunal absorption of an ethanol-containing nutrient solution (4% wt/vol, 4.06 kcal/min = 17.2 kJ/min, 1190 mosmol/kg) with the corresponding ethanol-free solution (2.64 kcal/min = 11.2 kJ/min, 160 mosmol/kg) and with another ethanol-free solution adapted in caloric load and osmolality (4.06 kcal/min = 17.2 kJ/min, 1160 mosmol/kg) by the addition of NaCl and glucose in eight healthy volunteers, using the intestinal perfusion technique. Ethanol added to a nutrient solution did not exert a significant effect on the net absorption of nutrients in the upper intestine. However, duodenal but not jejunal net water (p < 0.05) and sodium (p < 0.02) movements were significantly modified. Compared with the hyperosmolar ethanol-free solution, perfusion of ethanol induced in the duodenum a significantly lower (p < 0.001) net water and sodium secretion and higher absorption rates of total nitrogen and fatty acids (p < 0.001). The importance of the composition of control solutions in studies investigating the effects of ethanol in the gastrointestinal tract is emphasized.