Primary biliary cirrhosis (PBC) patients showed increased ceruloplasmin activity and Cu content in the serum as compared to the control group. Moreover, Cu, Fe, and Zn contents were measured in the livers of autopsied cases. The PBC patients showed increased Cu content and reduced Fe and Zn levels. In PBC cases, Cu transportation via bile is disturbed due to collapse of the interlobular bile ducts and consequently Cu accumulates in the liver. Thus, it is likely that serum ceruloplasmin activity increases to metabolize the accumulated hepatic Cu and that Cu content increases in the serum as a ceruloplasmin-bound form. Furthermore, reduction of Fe and Zn contents in the liver of the PBC patients indicated the possible relationship of ceruloplasmin to Fe and Zn metabolism as well as Cu metabolism.