To date there has been no research carried out in respect of the contribution being made by the independent sector to medium-secure psychiatric care. There are also no published studies comparing the provision of the independent sector with that of the public sector. As such this is a neglected field of study. This paper examines the characteristics of patients admitted to one independent medium-secure psychiatric hospital and two regional secure units in terms of their demographic characteristics, source, detention under the Mental Health Act, 1983, psychiatric diagnosis, criminal history and discharge. The results of the study are tested for their significance using the chi-square distribution. There is discussion of how the independent sector may be providing a service either unavailable within the National Health Service or for which the National Health Service is unsuitable in terms of patients either requiring medium- to long-term hospital care in conditions of security or those who cannot live independently and therefore require 'asylum', which is no longer an option within the National Health Service. In this sense, the independent sector could be seen as meeting a national need by acting as a 'safety valve' for National Health Service facilities.