Eating disorders (ED) is an important cause of physical and psychological morbidity in 21st century mental health. Recent advances of day treatment for eating disorders in North America, Germany, and Australia advocate us to investigate the utility and possibility of the Day Hospital Program (DHP) in Japan. We reviewed previous reports and summarized the advantages and disadvantages of this approach. Also, we conducted a preliminary survey to clarify the detailed application of the DHP by sending a questionnaire to University hospitals, registered institutes of the Japanese Association of Psychosomatic Medicine, and prefectural mental health and welfare centers. The results revealed the strong need for the DHP for ED (about 75%), strong expectations to link hospitalization and outpatient treatment, and the strong possibility of a multimodal approach. The survey showed the importance of CBT, psychoeducation, and other modalities including nutritional education, exercise, or the family approach. Various types of structures were proposed concerning the duration of a session or treatment (half day and 2 or 3 times a week) and numbers of members (about 6 to 10). Over 75% of the participants answered regardless of the inclusion of diagnostic criteria, which exceeded our expectations. Economic background is one of the problems left pending. Based on the data, we discussed the potential and problems of the DHP in Japan.