Although different methods have emerged over time, the vaginal cytology method, which is used to monitor the condition of the female genital canal, is often preferred because it is easy and practical. In 1917, after Stockard and Papanicolaou discovered that guinea pig vaginal lumen epithelial cells change according to the state of the ovulation cycle, the oestrus cycle exhibiting has become an essential part of the female genital system studies. Various factors affect the accuracy of results, including timing, method of smear sample collection, and the practitioner's experience in demonstrating vaginal cytology. The oestrus cycle shows four basic phases: proestrus, oestrus, metestrus, and diestrus, in rats and mice. Each phase of the cycle has a different dominant cell type and density. In this review; In addition to the methods of taking smears from mice and rats and the characteristics of the estrous cycle phases, there is information on the use of the data from experimental studies. Also, this study aims to provide a comprehensive perspective to researchers who will work with female subjects by emphasizing the points to be considered in terms of monitoring the dynamic changes in the female reproductive system and correct planning and evaluating the results of experimental studies.