Acute rejection is an important risk factor for allograft failure. Renal biopsy is the best method to predict out come of acute rejection, although; its complications as AVF, even graft loss. Some studies have highlighted the role of urinary IL-18 measurement which elevated in acute kidney rejected allografts as; compared with non-complicated kidney transplanted allografts. We study value of urinary IL-18 as; a non-invasive tool for early diagnosis of acute rejection or chronic allograft nephropathy.