Gardaí have estimated 25,000 people have attended a “Vigil for life” event to highlight opposition to any change on abortion legislation in Dublin.
Organisers said the event, which began in Merrion Square, was intended as a means to express concern about and opposition to plans to legislate for abortion in certain circumstances.
Afterwards, organisers said they were thrilled with the high turnout.
A series of speakers addressed the crowd from a specially-erected stage on Merrion Square.
They included various representatives of anti-abortion groups, as well as Tyrone football manager Mickey Harte.
"Ireland is almost unique in the Western world in looking out for, and fully protecting, two patients during a pregnancy - a mother and her unborn child," Mr Harte said.
"We are here to oppose the unjust targeting of even one unborn child's life in circumstances that have nothing to do with genuine life-saving medical interventions".
Caroline Simons of the Pro Life Campaign told the crowd that claims by the Government that abortion was needed to treat threatened suicide in pregnancy had been "completely demolished at last week's Oireachtas hearings on abortion".
"There is no evidence whatever that suggests that abortion reduces the mental health risks of unwanted or mistimed pregnancy. But there is evidence that abortion increases the risk of future mental health problems for a significant number of women.
A smaller group of around 200 pro-choice campaigners staged a counter demonstration nearby.
Abortion rights meeting
Earlier, over 100 activists gathered in Dublin to plan a campaign aimed a securing abortion rights for Irish women.
The newly-formed Abortion Rights Campaign says forthcoming legislation on abortion must allow doctors to perform terminations in situations where risk to the life of the mother is not immediate or inevitable.
It said such circumstances would include cases of rape, incest, fatal foetal abnormality or when a woman chooses not to continue with a pregnancy.