A simple and rapid staining technique was developed to confirm mating in Wistar rats. The study involves collection of vaginal smear from six adult female Wistar rats and the stages of the estrous cycle were determined by vaginal exfoliative cytology technique using Field stains. The Vaginal epithelial cells are classified as basal, intermediate, superficial intermediate, superficial and cornified by microscopical examination of stained vaginal smears. Proestrus females were co-habitat with adult Wistar male at the ratio of 2:1 and mating was confirmed by presence of sperms in the vaginal smear. The day on which sperm cells were observed in the vaginal smear was considered as day zero of pregnancy, after which the female rats was separated from the male rat. Out of the six female rats exposed to male, five female rats whose vaginal smears were positive for sperm cells were confirmed pregnant by ultrasonography. This study concludes that the Field staining can be used as a simple, rapid and less expensive technique to confirm mating by vaginal exfoliative cytology in rats.