1. In mental patients with rheumatic brain disease the sedimentation rate was slightly or moderately increased in 85.7 percent. The white blood count was over 10,000 cells in 30 percent of such cases, emphasizing that the sedimentation rate is a more sensitive index of activity of the infection in subclinical rheumatic fever than the leukocyte count.2. In 4 patients with rheumatic encephalopathy, who had increased sedimentation rates, a correlative histologic study disclosed rheumatic activity on the heart valves and in the vascular system of the brain, kidneys, spleen, etc.3. Greater familiarity with the existence of subclinical rheumatic fever in apparently physically healthy mental patients, in the presence of rheumatic heart disease, will bring nearer the time, when this group of patients, in whom rheumatic fever has affected both the heart and the brain, will be accurately recognized.4. The sedimentation rate is of little value in contributing to the differentiation of patients with rheumatic encephalopathy from other mental cases.Abstract Teaser