Jamie Heaslip aims to return for the game against France
Ireland will be without Jamie Heaslip, Shane Horgan, and John Hayes for the Six Nations Championship opener against Italy in Rome on 5 February.
Horgan (knee) and Hayes (groin) are also expected to miss the clash with France a week later.
Leinster number eight Heaslip, who has been struggling with an ankle problem, could return to face the French.
Andrew Trimble, Rob Kearney and Geordan Murphy had already been ruled out of the Italy game because of injury.
Ulster wing Trimble misses out after breaking a bone in his right hand.
Trimble picked up the injury during Ulster's Heineken Cup win over Aironi on Saturday.
Stephen Ferris and Tommy Bowe are injury doubts for the Rome encounter.
Leinster wing Horgan and Munster prop Hayes were both replaced at half-time in Heineken Cup games at the weekend.
Heaslip's injury has kept him out of Leinster's Heineken Cup games since Christmas.