14C-Fumonisin B1 (FB1) was produced by Fusarium proliferatum M-5991 in modified Myro liquid medium and purified to >95% purity with a specific activity of 1.7 mCi/mmol. Nine male and nine female F344/N rats were each dosed by gavage with 0.69 μmol of 14C-FB1, 14C-hydrolyzed FB1, or 14C-FB1-fructose/kg body weight. Urinary excretion of 14C-FB1 and 14C-FB1-fructose was 0.5% and 4.4% of the total dose, respectively, and was similar between male and female rats. Urinary excretion of 14C-hydrolyzed HFB1 was significantly greater (P > 0.05) in female rats as compared with male rats (17.3% vs 12.8% of the total dose, respectively). There were no significant (P > 0.05) differences in biliary excretion of the three fumonisin compounds with a mean of 1.4% of the dose excreted at 4 h after dosing. Lesser amounts continued to be excreted up to 9.25 h after dosing. Although biliary excretion of the14C-FB1, 14C-hydrolyzed FB1, and 14C-FB1-fructose was similar, increased urinary excretion of the 14C-hydrolyzed FB1 as compared to 14C-FB1 and 14C-FB1-fructose indicated a greater absorption of the hydrolyzed form.