Sligo-Leitrim TD Martin Kenny has confirmed a gun threat was made to his office in Leinster House.
The Sinn Féin deputy says a person rang the office on Tuesday morning.
The caller made threats against TDs and the gardaí.
An investigation's now underway following the call.
Deputy Kenny said: "A member of my staff took the call.
"The person had a conversation for about 10-15 minutes, and in the course of that conversation made threats against the gardaí and Leinster House in general.
"We don't know how serious any of this is, but we have to take everything like that seriously. The protocol is that we inform gardaí and Leinster House, and we've done that."
Yesterday's call comes two years after an arson attack on Deputy Kenny's car in Co Leitrim.
The Sinn Féin TD says these incidents show why TDs need to be careful about their security.
He observed: "We all know there are people out there who have got some sense of, I suppose, macho ability about them that they would take on to do things like that - like what happened with my car, or even protests we see at TDs' houses.
"Usually these are people from the far-right: they come with a particular agenda, and their agenda is hate and fear. They're about bringing the country down a road nobody wants to go down."