More recent studies indicate that immune cells which secrete their secretory products or cytokines play an important role in reproductive system. In our study, immune cell populations (CD8(+) T lymphocytes, CD68(+) macrophages, plasma cells, siderophages, eosinophils) and expression of major histocompatibility complex (MHC) class I and class II were examined in female reproductive tract during follicular (n=13) and luteal phase (n=10). Plasma cells and eosinophil granulocytes are present in few numbers in luminal epithelium, but abundant in longitudinal muscle layer of uterus, whereas siderophages are the dominant cell type in stroma. Moreover, MHC-I and -II+ cells are expressed by individual cells in organ layers, while CD8(+) T cells and CD68(+) macrophages are dominant in epithelium and muscle layer, respectively. In conclusion, we did not found significant changes in immune cells according to follicular and luteal phases, but localization and numbers in each organ have changed according to both organ and layers. These results indicate that these factors may play a crucial role not only to generate an immune response but also to have a role in regulation of physiological functions in female reproductive organs.