The fate of sucralose was investigated in rats following single intravenous or oral doses of 2-1000mg/kg. Following intravenous administration (2-20mg/kg) approximately 80% of the dose was eliminated in urine with 9-16% in the faeces. In contrast, only about 5% of oral doses (10-1000mg/kg) was recovered in the urine, indicating that sucralose is poorly absorbed from the intestinal tract. After both intravenous and oral administration, the radioactivity excreted in urine and faeces was mainly unchanged sucralose. Two minor radioactive urinary components were observed, which together accounted for less than 1% of the administered dose. Rats which had been given high concentrations of sucralose (3%) in the diet for more than 18 months showed a similar metabolic profile, demonstrating that metabolic adaptation of the gut microflora or mammalian enzymes had not occurred during the treatment period.