Objective: The aims of this study were to assess the procedures for involuntary admission to both public and private psychiatric hospitals as determined by the Mental Treatment Act, 1945 which is one of the oldest pieces of mental health legislation in the EC. Method: Over a prospective five month period all involuntary admissions to both a public and a private hospital in Dublin were studied. Social-demographic data and clinical features of 54 involuntary admissions were recorded and analysed. Results: 11.2% of public admissions were involuntary as were 3.4% of admissions to the private hospital. The most common diagnoses were schizophrenia and mania. 74.1% of the patients had been previously admitted. 81.5% of the patients were detained in hospital for less than three months although they were committed for a potential six months. There was no formal method of decertification. Conclusions: There appears to be little need nowadays for differentiating between legislation for public and private patients. The duration of the initial reception order should be reduced from six months to a period of forty-eight hours for initial assessment and treatment. If necessary this could be extended to three months. Formal methods for decertification are required. Mental health legislation in Ireland needs to be modernised.