The ability of secretions from the bovine oviduct to maintain the viability and motility of bovine spermatozoa was investigated by incubating frozen-thawed spermatozoa with oviductal flushings, uterine flushings, or the medium from cultures of oviductal epithelial cells and endothelial cells. The flushings obtained from both oviducts and uteri were effective for the maintenance of the viability and motility of spermatozoa, irrespective of the stage of the estrous cycle at which they had been collected. The flushings obtained from the ampullar region of oviducts at the follicular phase of the estrous cycle were most effective for the maintenance of viability and motile activity, for example, the forward motion of spermatozoa. Sperm viability and motility were also maintained by the medium from 6-hour culture of epithelial cells obtained from oviducts at the follicular phase of the estrous cycle. In contrast, the medium derived from bovine fetal artery endothelial cells had no significant effect on sperm viability and motility. These results suggest that the fluids of the female reproductive tract, in particular, the oviductal fluids at the follicular stage, provide a suitable environment for the maintenance of the viability and motility of bovine spermatozoa. It is also suggested that secretory product(s) of oviductal epithelial cells may play an important role in sustaining both the viability and motility of spermatozoa.