Green Party TD's Neasa Hourigan and Patrick Costello have had the party whip removed and been suspended for six months.
The parliamentary party agreed to the proposal last night, after the TD's voted against the government in the Dail.
They backed a non-binding Sinn Fein motion calling for the National Maternity Hospital to be built on public land - it passed after government TDs abstained.
The decision to suspend the two TDs means the government majority in the Dail has now been reduced to one.
Green Party chairperson, Senator Pauline O'Reilly, says it was a necessary step.