Bovine and human pancreatic ductal explants were maintained in long-term culture. Bovine ducts were cultured for 85 days, whereas human ducts have been cultured for up to 60 days. The explants all maintained good ultrastructural preservation for these periods and also incorporated radioactive precursors into protein, RNA, and DNA. Uncultured ducts, which were fixed for electron micrsoscopic study, demonstrated classical signs of reversible cell injury (dilated endoplasmic reticulum and swollen mitochondria), and cultured explants did not. However, the cultured tissues did show sublethal alterations such as the formation of numerous autophagic vacuoles and residual bodies and the accumulation of large lipid droplets. This study demonstrated the feasibility of maintaining pancreatic ducts in long-term explant culture, which enables them to be used in experimental studies involving chemical carcinogens and in structural and functional studies.