Abstract. Ceruloplasmin fractions I(C‐C) and II(C‐D) have been estimated in patients with infectious hepatitis, liver metastases and cirrhosis of the liver. In infectious hepatitis and metastases serum ceruloplasmin content was increased and the percentage of fraction I(C‐C) was decreased; no correlation between these parameters could be found. In the group of cirrhotics mean serum ceruloplasmin concentration was normal but the mean percentage of fraction I(C‐C) was decreased. A positive correlation between these values could be demonstrated. Very low ceruloplasmin levels were found in some patients with the most severe form of liver cirrhosis; if this is the result of an impaired synthesis, it seems probable that especially fraction I(C‐C) is affected by this disturbance. The possibility that only fraction I(C‐C) is synthesized by the liver is discussed.