After days of standardized conditions of life and standardized diets, serum gastrin levels were measured in 6 patients with liver cirrhosis on 3 consecutive days and in 14 normal controls on 1 day. Blood samples were drawn every 4 h. In patients as well as in controls, a significant serum gastrin circadian rhythm was noted. The daily mean serum gastrin levels of patients were not significantly different from those of controls. These results suggest a secondary role of the liver in gastrin metabolism.