Objective: To assess the effects of relocation on the social behaviour and mental state of a group of 43 long stay psychiatric patients transferred from an old institution to a modern hospital. Method: Each patient was assessed using the MRC Social Behaviour Schedule and the Manchester Scale. Assessments were carried out prior to relocation and at six weeks and six months after transfer. Results: Some deterioration was apparent in the patients' social behaviour at six weeks following relocation but this trend was reversed to definite improvement at six months. There was an overall marked reduction in hostility and violence following relocation. Patients who showed most improvement in terms of social behaviour were the lower functioning group where greater emphasis was placed on promoting basic self care and social skills rather than on occupational therapy. Changes in mental state, following relocation, were minimal but a slight deterioration occurred especially in the area of negative symptoms. Conclusions: Relocations caused no serious adverse effects in the majority of these patients. The improvement observed in certain aspects of behaviour are attributable to the improved physical and psychological milieu of the receiving hospital.