The question of detaining elderly mentally ill patients against their wishes raises many ethically difficult questions. The author conducted a survey of the extent and purpose of the use of the Mental Health Act (1983) in a particular psychogeriatric hospital, focusing on the circumstances in which it was used, how often patients or relatives appealed against its use and the outcome of the appeal. The author found that the Mental Health Act was used in only 5% of patients, and Section 5(2) was used only once. This stands in marked contrast to the use of Section S(2) in adult general psychiatry, where one survey found it to be used in 7.2% of patients (Pourgourides et al., 1992). The powers of the Mental Health Act in the population the author studied were most frequently evoked to detain and treat patients who were suffering from self-neglect secondary to their mental illness rather than to prevent them from wandering and coming to harm. It would appear that in this population, the Mental Health Act is used to facilitate admission for assessment and treatment; once admitted, patients can successfully be managed without the need for further recourse to the Mental Health Act. Very few patients or relatives appealed against their detention, and in no case was the appeal successful.