The Pensions Board has said it is concerned that the number of people with occupational pension schemes has fallen by almost 40,000 since 2010.
Speaking at the launch of the Board's annual report, Chief Executive Brendan Kennedy said the number of active members of occupational pension schemes in April 2012 was 771,878, down 38,083 from 2010 figures.
He said that while the fall in occupational pension scheme membership could be expected as a consequence of declines in employment and contractions in the economy, it was a matter of serious concern.
Mr Kennedy stressed the importance of personal savings to provide for retirement in addition to the State pension.
The Board also revealed that it has succeeded in 26 prosecutions of pension law, with 36 more cases pending for 2012.
Earlier this month, the board published new rules for defined benefit pension schemes, 80% of which are in deficit.
Minister for Social Protection Joan Burton acknowledged that in many cases pension incomes will end up being below what was promised or anticipated.