The gastrointestinal absorption of lactitol has been studied in 6 healthy volunteers and 8 patients with cirrhosis. Following administration of lactitol 0.5 g/kg, no lactitol was found in serum. The urinary excretion of lactitol over 24 h ranged from 0.1 to 1.4% of the administered dose (0.46% in cirrhotics and 0.35% in healthy volunteers). Blood D- and L-lactate and plasma glucose did not increase following lactitol. The data indicate that lactitol was poorly absorbed from the gastrointestinal tract in healthy volunteers and patients with cirrhosis, and that the disaccharide did not disturb glucose or lactate homeostasis.