Sinn Féin's leader in the Dáil, Caoimhghin O'Caolain, was reportedly rushed to hospital last night after falling ill in his office at Leinster House.
Reports this morning say the Cavan-Monaghan TD became unwell at around 6pm and was attended by an ambulance crew before being taken to hospital.
His condition is unknown, but he was reportedly conscious throughout.
The 53-year-old underwent successful cardiac surgery earlier this year after suffering a heart attack.