The disposition of 200 mg/kg of 14C-labelled sucrose octa-isobutyrate (14C-SOIB), a component of sucrose acetate isobutyrate (SAIB), a beverage emulsion stabilizer, was studied in rats, dogs and monkeys. After oral administration of 14C-SOIB to three rats, 3-15% of the dose was excreted as volatile products, 1-2% appeared in urine and 78-93% was recovered in faeces. In dogs, recoveries of radiolabel in CO2, urine and faeces were approximately 1%, less than 2% and 77-94%, respectively. Monkeys excreted the majority of the dose in faeces; less than 2% of the administered radioactivity was eliminated in either CO2 or urine. The biliary excretion of radiolabel from 14C-SOIB was negligible in rats and monkeys; however, in dogs, 3-10% of the dose was excreted into bile. It was demonstrated by chromatographic analyses of faeces that 14C-SOIB was more extensively hydrolysed in the gastro-intestinal tract of rats and dogs than in monkeys. The results indicate that after oral administration, rats and dogs absorb SOIB following hydrolysis of the sugar ester in the gut. The proportion of the dose that is absorbed by the rat is oxidized to CO2. In the dog, little of the absorbed product is oxidized; rather, it is circulated through an enterohepatic pathway. In contrast, in the monkey, SOIB is not detectably hydrolysed in the gut or absorbed. These findings show that there is a species difference in the disposition of SOIB; the most salient findings relate to a difference in the disposition of SOIB in the dog compared with the rat.