Both Fitzgerald, who played in the first Test in South Africa three years ago, and O'Leary, who missed the tour through injury, have been placed in the Irish Wolfhounds squad by coach Declan Kidney.
There is no place for the injured Brian O'Driscoll and David Wallace and 2009 Lions skipper Paul O'Connell will lead Ireland into their World Cup revenge mission against Wales on home soil on the first weekend of next month.
"It's a new tournament for us and for everybody involved, so irrespective of the highs and lows of the World Cup, it is a fresh and exciting challenge for us," said Kidney.
"The tournament begins what is big year for us, with a three test tour to New Zealand to come in June and ranking points all important for the Rugby World Cup in 2015, but the Six Nations always stands out as high point.
"There have been some strong performances by players with the Provinces going really well. It always gives the squad a good boost when we have teams with players playing well in Europe before we step back up into the international scene."
Ireland Training Squad
Rory Best (Ulster), Tommy Bowe (Ospreys), Tom Court (Ulster), Sean Cronin (Leinster), Leo Cullen (Leinster), Gordon D'Arcy (Leinster), Keith Earls (Munster), Stephen Ferris (Ulster), Cian Healy (Leinster), Jamie Heaslip (Leinster), Shane Jennings (Leinster), Rob Kearney (Leinster), Fergus McFadden (Leinster), Conor Murray (Munster), Sean O'Brien (Leinster), Donncha O'Callaghan (Munster), Paul O'Connell (Munster), Ronan O'Gara (Munster), Eoin Reddan (Leinster), Mike Ross (Leinster), Donnacha Ryan (Munster), Jonathan Sexton (Leinster), Andrew Trimble (Ulster),
Paddy Wallace (Ulster)
Additional Players: Ian Nagle (Munster)*, Peter O'Mahony (Munster)*, Tiernan O'Halloran (Connacht)*, Paddy McAllister (Ulster)*, Andrew Conway (Leinster)*, Simon Zebo (Munster)*
Stephen Archer (Munster)*, Isaac Boss (Leinster), Gavin Duffy (Connacht), Luke Fitzgerald (Leinster), Chris Henry (Ulster), Denis Hurley (Munster), David Kearney (Leinster)*, Ian Keatley (Munster), Ronan Loughney (Connacht)*, Ian Madigan (Leinster)*, Mike McCarthy (Connacht), Kevin McLaughlin (Leinster), John Muldoon (Connacht), Tomas O'Leary (Munster), Eoin O'Malley (Leinster)*, Rhys Ruddock (Leinster), Mike Sherry (Munster)*, Nevin Spence (Ulster)*, Devin Toner (Leinster), Dan Touhy (Ulster), Damien Varley (Munster), Brett Wilkinson (Connacht)*
Not considered due to injury: Brian O'Driscoll, David Wallace, Darren Cave, Felix Jones, Jerry Flannery, Eoin Griffen*, Denis Leamy, Niall Ronan.
* denotes uncapped player