Minister for Health James Reilly will announce the opening of the first phase of the new Mater Hospital in Dublin later today.
The first phase, which includes a new out-patient department as well as catering and technical services, will fully open in June.
Phase two of the new €284m project - which includes a new emergency department, car park, operating theatres, ICU, radiology and single en-suite rooms - will be opened between July and December of this year.
The Mater Hospital currently admits around 16,500 patients every year.
It is estimated that the hospital treats in the region of 40,000 day patients and over 47,000 emergency department cases annually.
The development of the new hospital began in 2000.
Mater Hospital Chief Executive Brian Conlan has said that today is a "great day" for all patients and staff.
"We now have state-of-the-art, eco-friendly accommodation and facilities, creating a perfect environment for delivery of top class care to our patients provided by the best professionals in the business."
