The quantitative liver function, measured by the galactose elimination capacity (GEC), was determined repeatedly in 44 patients with cirrhosis during the course of the disease. After a median observation period of 57 months (range 28-85) 17 had died from liver insufficiency. GEC was found to be of prognostic value, as classification of the patient series on the basis of the median value of two extreme prognostic groups indicated that the survival of patients with GEC greater than 1.37 mmol . min-1 at entry was significantly larger than of patients with GEC below that value (p less than 0.05). The prognostic values of serum albumin and prothrombin were of the same order of magnitude. At repeated examinations during the course of the disease, the survivors always had higher GEC values than those who died from liver insufficiency. Among those who survived and those who died there were patients with both increasing and decreasing GEC values, but no significant changes were observed within the groups. The individual changes in GEC can result from changes in the balance between liver cell necrosis and regeneration, but the possibility cannot be excluded that changes are due to methodological problems in the determination of the quantitative liver function as measured by GEC.