Background. This paper presents our experience with cytologic examination of urine in diagnosing renal allograft dysfunction. Methods. The study group included 23 patients with renal allograft dysfunction, selected from 56 patients who underwent renal transplantation. Etiologic diagnosis was made according to the clinical picture, histological findings during allograft biopsy, and cytologic examination of urine. Urine sediment was obtained in cytocentrifuge and was air dried and stained with May Grunwald Giemsa. Results. Out of 23 patients with allograft dysfunction in 18 (78.3%) patient it was caused by acute rejection, and in 5 (8.9%) patients by allograft infarction, cyclosporine nephrotoxicity, acute tubular necrosis and chronic nephropathy. In eighteen patients (78.3%) cytologic examination of urine was pathologic, while in 16 (70%) clinical and histology findings coincided with urine cytology findings. Out of 18 patients with acute allograft rejection in 15 patients cytologic examination of urine coincided with acute rejection. Out of 7 patients with expressed cyclosporine nephrotoxicity, in 5 cytologic examination of urine confirmed the cause of allograft dysfunction, as well as in one of 2 patients with acute tubular necrosis. Cytologic examination of urine indicated parenchymal damage in 2 patients with reccurent disease (membranoproliferative and focal sclerosing glomerulonephritis). In 4 of 5 patients suffering from chronic rejection in a year’s monitoring period, urine sediment periodically consisted of lymphocytes, neutrophilic leucocytes, monocyte/macrophages, tubular cells and cilindres, without the predominance of any cell type. In 3 patients allograft dysfunction was caused by infective agents (bacteria, fungus cytomegalovirus). Conclusion. Cytologic examination of urine might be an alternative to histological in diagnosing acute allograft rejection and acute tubular necrosis or nephtotoxicity. Also it might indicate parenchymal disease while the importance of urine cytology in chronic allograft nephropathy needs to be investigated further.