The Taoiseach Mr Ahern will today address the Welsh Assembly.
Mr Ahern will hold meetings with Welsh First Minister Mr Rhodri Morgan and other ministers before addressing Assembly members.
Mr Ahern will also attend two events in Newport in south Wales aimed at boosting Wales's international profile.
Mr Morgan welcomed the visit, which takes place on St David's Day.
"We share so much in common with Ireland and cast envious glances at the way in which the country has developed one of the fastest-growing economies in Europe.
"Objective 1 funding from Europe gives us the opportunity to emulate our Celtic cousins and it is highly significant that as well as addressing the Assembly the Taoiseach will be participating in the launch of two important events to show what Wales offers the world," he said.
PA
