Few ultrastructural observations of hepatic parenchymal cells in cystic fibrosis (CF) have appeared in the literature. Utilizing a unique opportunity to examine freshly fixed hepatic tissue by transmission electron microscopy, we studied 12 patients dying with CF at Duke Hospital from 1979 to 1981 in order to identify possible abnormalities of intracellular architecture. The major findings include (1) intracellular fatty vacuoles, (2) distended bile ductules and bile ducts containing increased cellular debris, (3) profiles of distended rough endoplasmic reticulum containing material of medium electron density, and (4) membrane-bound deposits of electron-lucent material containing electron-dense cores resembling mucus. We suggest that the material seen within the cytocavitary network reflects a derangement of intracellular transport.