Joe Schmidt will have to plan the rest of his Six Nations campaign without Andrew Trimble and Ultan Dillane.
The IRFU have released a statement, after the squad gathered at Carton House yesterday evening after the round 17 fixtures in the Pro 12.
Andrew Trimble broke a bone in his hand in Ulster's win against Treviso at the Kingspan Stadium on Friday night and has been ruled out of the final two games.
Meanwhile, Ultan Dillane will undergo surgery this week for an ongoing shoulder issue and has been ruled out of action for 8-10 weeks.
It's not all bad news though.
Rob Kearney is expected to train fully tomorrow after suffering a groin injury.
Tommy Bowe is back in the squad for the final two games of the Six Nations against Wales and England.