Allograft rejection during the first year after renal transplantation can lead to persistent allograft dysfunction and reduced long-term graft survival. Thus, it is important to define early predictors of kidney damage, less invasive than allograft biopsy. Urinary glycosaminoglycan/proteoglycan concentration and distribution, N-acetyl-β-(D)-glucosaminidase (NAG), and monokine induced by IFN-γ (MIG) levels were evaluated in the immediate post-transplant and during a 1-year follow-up. We observed increased urinary levels of MIG, urinary trypsin inhibitor and its degradation products, the lack of urinary heparan sulfate excretion, and the decreased chondroitin sulfate relative content at day 1 post-transplant in most patients who developed complications in the postoperative period. Moreover, urinary MIG levels showed significant correlations with NAG, C-reactive protein, and GFR at day 1 post-transplant. The monitoring of glycosaminoglycan/proteoglycan urinary pattern and the levels of urine MIG could serve as useful markers for predicting possible complications of transplantation, unraveling an early inflammatory state, on whose basis the immunosuppressive therapy could be appropriately modified.