The aminopyrine breath test was assessed as an indicator of liver damage in a consecutive series of 49 chronic alcoholics admitted for detoxification. Mean 14CO2 excretion for those with compensated cirrhosis was 1.6%, compared with 6.8% for those with histologically normal livers, 4.3% for those with fatty change, and 4.0% for those with fatty change and fibrosis. All patients with cirrhosis had a value below the lower limit of normal (3.2%), whereas only 6 of the other patients had a subnormal value. Repeat studies after 7-10 days' abstinence showed that 14CO2 excretion increased in patients with compensated cirrhosis. In view of the poor prognosis of alcoholic cirrhosis once decompensation occurs, early identification of those at risk is important. The aminopyrine breath test was found to be a conventient and sensitive method for detecting early cirrhosis and lends itself as a screening procedure in the management of alcoholic patients.