Abstract: AIM: To monitor the concentration of tacrolimus in whole blood in liver transplant recipients and establish an optimal therapeutic window of tacrolimus, in order to provide information for rational usage in clinic.METHODS: The whole blood concentrations of tacrolimus were measured by ELISA.The levels of tacrolimus in 1190 samples from 138 liver transplant recipients were compared and studied.RESULTS: The whole blood concentration of tacrolimus is gradually decreased with time after operation.The optimal therapeutic window of tacrolimus for liver transplant recipients was 8 -15 μg·L^-1within 1 month after operation, 6 -12 μg·L^-1 from the 2nd to 3rd months, 5 -10 μg·L^-1from the 4th to 6th months and 3 -8 μg·L^-1 after 6 months, respectively.CONCLUSION: It is necessary to routinely monitor blood concentration of tacrolimus.The satisfying therapeutic effects will be obtained if dosage regimens will be individualized according to optimal therapeutic window.

Key words: tacrolimus, therapeutic drug monitering, ELISA