Jack and Sarah were the most popular babies' names registered last year, according to CSO figures released this morning.
Jack returns to the top position it last held in 2005 and Sarah retains the top position it held in 2006.
There were 1,073 boys named Jack in 2007, 108 more than the number of boys named Seán, in second place at 965.
The next most popular names for boys were Conor (821), Daniel (725) and James (713)
There were 656 girls named Sarah, 24 more than the number of girls named Emma, the second most popular girls' name. In third, fourth and fifth place were Ella (601 babies), Katie (566) and Sophie (556).
Four of the top five boys' names (Jack, Sean, Conor and James) have been in the top five since 1998, with only their order changing from year to year, the CSO said.
Daniel is a new entry to the top five at number four but has been ranked sixth from 2002 to 2006.
There were six first-time entries to the top 100 for boys: Rhys, Oliver, Jayden, Louis, Lucas and Jacob.
The highest new entries into the list at number 76 were Rhys and Oliver.
There were also six first-time entries to the top 100 for girls: Brooke, Millie, Taylor, Muireann, Freya and Maya. Sara returned to the top 100 after a two-year absence and the name Lara returned to the list after a four-year absence.
The highest new entry for baby girls' names was Brooke, rising from 289th place in 2002 and 133rd in 2006 to number 73 last year.
The names Millie and Muireann rose the most places up the 'baby chart', up 39 places each to number 84 and 91 on the list.
Broken down by region, Jack was the most popular boy's name in seven of the eight regional authority areas. The exception was Dublin, where Seán was top of the list.
For girls' names, Sara was most popular in the Border and south-west regions. Emma was the top pick for parents in the west and mid-west regions; Ella was most popular in the mid-east and south-east and Katie was the top of the list in the midlands.
In Dublin, Sophie was the most popular girl's name.
These results are based on an analysis of the first names recorded on birth returns for registration and vital statistics, begun by CSO in 1998.
Top ten registered names for boys
1 Jack 1,073
2 Seán 965
3 Conor 821
4 Daniel 725
5 James 713
6 Adam 485
7 Ryan 553
8 Luke 538
9 Cian 527
10 Michael 521
Top ten registered names for girls
1 Sarah 656
2 Emma 632
3 Ella 601
4 Katie 566
5 Sophie 556
6 Ava 555
7 Aoife 527
8 Emily 475
9 Grace 473
10 Kate 426