The man was crossing the road at Parnell Square West in Dublin's north inner city when he was struck by a car which was being driven by a man and his heavily pregnant wife.
It is understood that the couple were on their way to or coming from the Rotunda Hospital.
After the man was hit, another car then drove over him. He was declared dead at the Mater Hospital a short time later.
"It appears the man was clipped by one car and knocked into the roadway, and the second car coming behind then ran over him. It's very tragic," said a source. "This was a most tragic and unfortunate incident.
"The occupants of both cars are extremely traumatised and the pedestrian suffered terrible injuries."
The accident happened at 12.15am. At the time of going to press, the man had still not been identified.
A garda spokesman said: "A male pedestrian in his 50s was seriously injured when he was struck by two cars. He was taken to the Mater Hospital where he was later pronounced dead."
Gardai are appealing for witnesses to contact Store Street Garda Station on 01-6668000, the Garda Confidential Line on 1800 666 111.