To explore the role of miR-223 in the acute rejection after kidney transplantation.33 patients who received kidney transplantation in our hospital within a year were collected and 12 of them appeared acute rejection within 1 month after surgery. In all the patients, the peripheral blood miR-223 level was collected and detected by blind arrangements. Furthermore, PBMCs from healthy volunteers were also collected and stimulated by PHA and then miR-223 level was measured.In the peripheral blood cell, the miR-223 was increased 2 times after acute rejection, as well as 3. 76 times after PHA treatment.Furthermore, using miR-223 predicts AR had a specificity of 90% and sensitivity of 92%.The miR-223 may have significant role in the acute rejection of kidney transplantation.