We assessed the effect of 2-week oral treatment with chlorfenvinphos, cypermethrin and their mixture in a dose of 5% LD50 on the intestinal transport of L-leucine (Leu) and L-methionine (Met) in male Wistar rats. Both in vitro (jejunal slices) and in vivo (intestinal perfusion) methods were employed in the study, using Leu and Met labelled with 14C as markers of the investigated processes. Additionally, in the in vitro study, concentrations of two amino acids were measured in the whole blood, serum, liver and perfused segment of the intestine. In the in vitro study the kinetic constants describing the active and passive Leu and Met uptake were determined. The active uptake was found to be particularly affected by oral intoxication with chlorfenvinphos, cypermethrin and their mixture. This susceptibility was seen as major alterations in the parameters of active uptake, i.e. Jm and Ki constants in the pesticide-exposed groups as compared to controls. In the in vivo study we found a decreased rate of Leu and Met disappearance from the intestinal lumen, decreased blood concentrations of Leu and Met and decreased liver content of Leu in the pesticide-exposed groups as compared to controls. The findings allow the conclusion that oral administration of chlorfenvinphos, cypermethrin and their mixture in a dose of 5% LD50 impairs the intestinal transport of Leu and Met and alters their distribution in the rodent body.