Abstract: Aim To observe the relation between the blood cysclosporine concentration.Methods The therapeutic drug monitoring data of cyclosporine in 97 kidney-transplanted recipients in 8 weeks, from May 1995 to October 1996, were analysed retrospectively.The recipients were sorted in three groups，the normal group, the acute rejection group and the acute toxicity group.Blood cyclosporine concentration was measured by FPIA with monoclonal antibody reagent.Results In normal group, 62 recipients had good kidney function, with average daily dose of cyclosporine 5.2±1.9mg/kg·d, the blood concentration of cyclosporine was 309.85±131.69μg/L ;In acute rejection group, the average daily dose in 26 recipients was 4.8±1.6mg/kg·d, the blood concentration of cyclosporine pending rejection episode was 165.80±123.13μg/L;In acute toxicity group, the average daily.dose in 9 recipients was 6.2±1.0mg/kg·d, the cyclosporine blood concentration pending toxicity episode was 556.51±102.50μg/L.There was no sigificant difference among the three groups on the average daily dose of cyclosporine (P>0.05).However，the blood concentration of cyclosporine in three groups varied greatly and there was significant difference among them(P<0.05，even P<0.01 between acute rejection group vs toxicity group).Conclusion In therapeutic drug monotoring of cyclosporine measurement of blood drug concentration is extremely important.More acute rejection episodes occur with low blood concentration of cyclosporine, while more toxicity episodes happen with high blood concentration.

Key words: cyclosporine, therapeutic drug monitoring, kidney transplantation