Seventeen insurance company employees were selected consecutively from a list of patients with elevated mean corpuscular volumes on routine automated blood counts. Chronic alcohol consumption was present in 16 patients and was heavy in 11 patients. Nine alcohol consumers had clinical evidence of mild hepatic disease and four had abnormal liver function tests. Mild anemia with a red cell count between three and four million was present in only three patients. Folate deficiency was present in only one and B12deficiency in none of the 15 in whom these parameters were measured. Hemolysis was absent in these patients. There appears to be an unexplained association between macrocytosis and mild alcoholic disease of the liver in usually nonanemic and otherwise healthy subjects. The mean corpuscular volume as determined by routine Coulter counts may be a useful screening procedure for alcohol abuse.