Studies have shown that patients who do not produce donor specific and /or panel reactive anti-HLA antibodies have a longer graft survival. The purpose of this study was to evaluate the posttransplant humoral immune response towards HLA-class I antigens and the measurement of the serum creatinine levels which are used in monitoring posttransplant function of kidney. Serum samples from 132 renal transplant recipients were screened for preformed anti-HLA class I panel reactive antibodies (PRA) by means of microlymphocytotoxicity assay. The results revealed the presence of PRA in 26 (19.7%) out of 132 transplanted patients. Graft function was evaluated by measurement of serum creatinine levels which revealed the mean of 1.75 mg/dl (SD: 1.08). Because of clinical significance of presence of different PRA amounts (>10%, > 20% and >50% of panel reactivity) in patients, correlation with kidney function status was analyzed. The obtained data highlighted a higher presence of serum creatinine levels in PRA-positive patients compared to negative patients (P<0.01). These results (and further studies for class II, ...) can be used to implement new therapeutic strategies to curtail post transplant alloantibodies production and better allografts survival.