This experiment has been carried out to study histological changes of vaginal epithelial cells in rabbits during pregnancy, using 26 heads of 8 month-old does. Vaginal smears were collected from vaginal lumen before copulation and on the 7th day of pregnancy. Tissue samples were collected from vagina and vaginal vestibule before copulation and on the 7th, 14th, 21st, and 28th day of pregnancy. The results observed were as follows. 1. Vaginal vestibule epithelium shoved considerable decrease is the number of cell layers from 5-15 during progestational phase to 1 or 2 layers on the 28th day of pregnancy. Vaginal epithelium of 1-3 layers remained constant throughout pregnancy. 2. Vaginal vestibule epithelial cells were changed from squamous, circular and columnar type of non-pregnancy into squamous and cuboidal or columnar typer of pregnancy, while epithelial cells were changed from cuboidal or columnar type into squamous or columnar type. 3. In vaginal smears, cornified cells were found in the progestational period, but they were no longer observed on the 7th day of pregnancy. In non-pregnancy, cornification-sloughing was observed in vaginal epithelium; and also mitotic figure in qasal layer, both of these were observed scarcely any after the 7th day of pregnancy. 4. Epithelial ridges showed regular figure in non-pregnancy, but the size of them were not constant after the 7th day of pregnancy. The number of them began to decrease only after the 14th day and showed apparent decrease on the 28th day of pregnancy. 5. Vaginal wall began to enlarge from the 14th day, especially after the 21st day of pregnancy. Lamina propria was outstandingly atrophied after the 21st day of pregnancy. 6. It is considered that pregnancy diagnosis would be possible within 1 week of pregnancy by observing the increasing trend of viginal mucus and the decreasing trend of cornified cells in rabbit.