Secondary personality change (SPC) can be caused by various medical conditions and is rarely reported. We retrospectively investigated the prevalence, characteristics, clinical features and treatment response in psychiatric in-patients with a primary diagnosis of SPC. Ten cases of SPC were diagnosed in a series of 5774 patients. Head trauma was the leading cause of SPC. Impulsivity, affective lability and aggression were commonly found in these SPC patients. After medication treatment, all SPC patients had mild to moderate improvement. Secondary personality change is rarely diagnosed in psychiatric in-patients and responds poorly to medication treatment.