Almost 70% of employees at the Department of Health took sick leave last year.
New figures from the Department of Social Protection also show that the cost of benefits for people who cannot work due to illness exceeded €900m last year - an increase of almost 8%.
The data found that in the HSE, the absentee rate has fallen for the year to the end of June.
In the Department of Education, 680 staff members took sick leave in 2008, down from 692 in 2007.