Approaching 1pm, there has been a turnout of 20% in parts of Dublin.
The situation is similar in areas in Tipperary, Waterford, Galway, Wexford, Limerick, Clare, Laois and Offaly, where turnout is in the mid to high teens.
Some presiding officers say this ranks as one of the busiest mornings they have ever seen, with some saying a greater number of younger voters are casting their ballots than usual.
Turnout in some rural areas is lower, with South Kerry, North Mayo, South Donegal and North Monaghan experiencing turnout between 5 and 10%.
Friday, May 22, 2015
Good news so far for "Yes" supporters in Irish gay marriage referendum
The Irish broadcasting network RTE reports a "brisk" turnout with especially heavy voting in the locales and demographics that "Yes" supporters want to see and less where they don't: