There were 429 civil partnerships in 2012, with 263 involving men and 166 involving women, according to the Central Statistics Office.
Over 298 (69%) of the same-sex couples that entered into civil partnerships in 2012 reside in the Leinster area with 148 (34%) living in Dublin city.
Of the 858 individual partners, 60 were divorcees, while the rest were previously single.
There were 20,713 marriages in 2012, up over 4.3% from 2011 when 19,855 couples married.
The average age of the grooms in 2012 was just under 35, while the average age of brides was 32.6 in the same year.
The average age of the groom in civil marriages was 37.9 years, while the average age of the groom in Catholic marriages was 33.2 years.
August was the most popular month for marriage that year, with 3,046 couples tying the knot. January was the least popular month with 449 marriages.
Friday and Saturday were the most popular days of the week to marry, with seven out of ten marriages occurring on those days.
In 63% of marriages, the groom was older than the bride across all age groups except in the case of grooms under 25.