Both increased knowledge of the importance of cytokines in the activation of the immune system and the development of specific and accurate assays for their quantitation now offer the possibility of their study as markers to predict or diagnose renal allograft rejection. From our study, we concluded that TGF-β 1 and PDGF are two of the most important cytokines that have been implicated in the development of renal allograft fibrosis and rejection. Measuring these two cytokines in the serum and urine of renal allograft recipients can help to differentiate between the effects of immunosuppressive drugs and the occurrence of true rejection. Future studies are recommended on other cytokines, to find out if there is any correlation between the cytokines and renal allograft rejection, and to detect if these cytokines can be used as monitor for the immunological state of impending graft rejection.