BackgroundSomatization is produced due to the summation of psychological factors, irrespective of the presence or absence of physical factors. A group of diseases with severe pain and other disorders exhibit so-called Medically Unexplained Symptoms (MUS), and the characteristics of patients with MUS are largely unexplained. In this paper, the characteristics of a series of new patients with somatization treated in a Japanese university hospital are discussed.MethodThe subjects were 871 patients who newly visited the Department of Psychosomatic Medicine, Toho University Omori Medical Center between January and December of 2015. Under the assumption that the definition of somatization is same as that of MUS, the correlation between somatization and the age, sex, academic background, chief complaints, reasons for visiting the medical center, diagnosis, symptoms, presence or absence of a referral form, continued treatment after the first visit, and marital status of these patients at the time of their respective examinations were evaluated.ResultsOf the patients studied, 68% suffered from somatization. Among them, 11% met the definition of Functional Somatic Symptoms (FSS) and 74% had somatization associated with mood disorder or anxiety disorder. Digestive symptoms were reported by 33%, headaches by 24%, and unusual sensations by 21%. Whereas no correlation was found between somatization symptoms and the patients’ academic background, marital history, or medical history after the first visit, a positive correlation (p < 0.05) was found between somatization and patients who had been referred by their doctor.ConclusionMany of the studied patients who suffered from somatization, regardless of age and sex, were referred to us by doctors from other hospitals. It was concluded that many patients difficult to diagnose or deal with are referred the Department of Psychosomatic Medicine of Japanese university hospitals, thus these hospitals must assume great responsibility for preventing mistaken diagnoses by conducting effective psychological treatment and thorough medical examinations.