The production of immunoreactive-endothelin by bovine oviduct epithelial cells in culture was studied. The minimum amount of endothelin detected in the supernatant of cultured bovine oviduct epithelial cells after 6 h of incubation was 97.3 +/- 10 pg endothelin mg-1 protein and the amounts increased significantly (P < 0.01) with time of incubation. Pretreatment of bovine oviduct epithelial cells with the calcium ionophore A23187 increased the production of endothelin (P < 0.05). These results provide the first evidence that bovine oviduct epithelial cells produce endothelin and, therefore, may be locally involved in the muscular oviduct wall contractility and play an important role in the transport of gametes and embryos.