Last year 329,706 working days were lost to industrial disputes, according to new figures from the Central Statistics Office.
There were a total of 23 industrial disputes in 2009, compared with 12 disputes in 2008, when 4,179 days were lost.
Public sector disputes accounted for 75% of the total days lost, and 95% (265,400) of the total number of workers involved.
The one-day national public sector strike on November 24 involved 265,400 workers and accounted for 237,268 days lost.
The highest number of those workers were in education; health and social work; and public administration and defence.
The CSO calculates the number of days lost by multiplying the number of people involved by the number of normal working days during which they were involved in the dispute.
