Statistical studies on anorexia nervosa in Japan were carried out by our research group. Questionnaires were sent to physicians at 1,030 representative institutions throughout Japan and data were collected from 315 institutions. The total number of patients with anorexia nervosa in 1981 was 940 outpatients and 372 inpatients. The number of patients in 1981 was twice as high as in 1976. Detailed data on 1,011 patients were investigated. As most of the patients had certain endocrinological abnormalities which improved after weight gain, indications are that at least a part of the endocrinological abnormalities might be secondary changes due to weight loss.