Fumonisin B1 (FB1), the major compound in the fumonisin group of secondary metabolites of Fusarium moniliforme Sheldon, is associated with some human and animal diseases. After intraperitoneal dosing to rats (7.5 mg/kg), FB1 was rapidly absorbed and reached a maximum concentration in plasma within 20 min after injection. Thereafter, it underwent rapid removal from plasma, displaying a mono-exponential elimination phase that fitted a one-compartment model with a half-life of 18 min. Collection of 24- and 48-hr urine samples indicated that only 16% of the applied dose was eliminated unmetabolized in urine, all within the first 24-hr period following dosing. In contrast to this, a similar dose of FB1 given by gavage resulted in the recovery of only 0.4% of the FB1 in urine.