The fate of ochratoxin A (OA) injected iv was studied in both albumin-deficient and normal rats. The OA concentration in plasma decreased to a level below 0.5 micrograms/ml within 10 min of the injection in albumin-deficient rats, but remained above 50 micrograms/ml for 90 min in normal rats. The OA concentrations in bile and urine, and the rate of OA excretion in these fluids were 20-70-fold higher in albumin-deficient than in normal rats. The results demonstrate that a primary effect of albumin binding on OA is to retard its elimination by restricting the entry of OA into the hepatic and renal cells.