This paper was attempted to study on the effect of metoclopramide or propantheline on the absorption rate and bioavailability and pharmacokinetic parameter of fluorouracil in rats and rabbits. The result are as follows : Metoclopramide increased the absorption rate of fluorouracil but propantheline decreased in situ experiment with rat small intestine. Metoclopramide increased the blood level and relative bioavailability and absorption rate constant of fluorouracil in rabbits. Prolonged the peak blood level (tmax) and decreased the absorption rate constant (Ka) but did not affect the blood level and relative bioavailability of fluorouracil in rabbits. As a matter of fact, it is considerd that the coadministration of metoclopramide or propantheline is more desirable than the single administration of fluorouracil for available dosage regimen.