ObjectivesZZDelirium is commonly seen in clinical settings, and it can substantially influence the prognosis of patients. In this study, we investigated delirium with respect to its severity, classification and characteristics on each subtype. MethodsZZSeverity of delirium was examined in delirium patients, who were referred to the department of psychiatry in a general hospital for multidisciplinary treatment. After classification based on subtypes, factors influencing these aspects of delirium were examined. ResultsZZAmong the 193 consultation-liaison patients referred to the department of psychiatry in a general hospital, 61 patients (31.6%) were diagnosed with delirium. Compared to patients in the non-delirium group, patients in the delirium group were older, had a shorter education period, and medical history of surgery. Among the delirium patients, the hyperactive subtype was found to be the most common (57.4%) and patients with the mixed subtype showed the highest severity score for delirium symptoms. In addition, the patient with the hypoactive subtype had a higher frequency of medical history of depression compared to those with the other subtypes. ConclusionZZPeople with symptoms of hypoactive delirium can be misdiagnosed due to recurrence of depression, therefore, careful examination is required, particularly in patients with a history of depression.