Objective To investigate the expression of the immune cells and their roles in the kidney of patients with severe acute respiratory syndrome（SARS）by immunohistochemical staining. Methods Immune cells of the kidney in 6 SARS cases and 3 control cases were labeled by immunohistochemical staining, and positive cells were morphologically observed and quantitatively analyzed by image analysis system. Results CD68 positive monocytes/macrophages increased significantly in SARS cases（EM>P/EM>0.05）, CD3 positive T lymphocytes, CD20 positive B lymphocytes and S100 positive dendritic cells, however, had no differences between SARS cases and control cases（EM>P/EM>＞0.05）. Conclusion Monocytes/macrophages are major immune response cells in the SARS kidney which indicates that monocytes/macrophages may play an important role in the pathological changes of the SARS kidney. It is