To make the differentiation of kidney transplant acute rejection and ciclosporin (CS) nephrotoxicity urine cytology by classical Papanicolaou with immunocytochemical stain has been performed. Increased numbers of renal tubular cells with lymphocytes and monocytes were found in both rejections and CS toxicities. CS toxicities were associated with increased numbers of proximal tubular cells. In immunocytochemical stain, increased numbers of CD25 and CD8 positive cells as well as increased ratio of HLA-DR/cytokeratin positive cells were typically found in rejections. It is concluded that the proposed analysis of urine cytology is a non-invasive and reliable method for daily graft monitoring of acute rejection and CS toxicity.