Dublin City Council (DCC) has 7pc less social housing units than it had on the books in 2010, the Herald can reveal.
Information provided by the city council to councillor Ruairi McGinley shows that the stock has decreased by some 1,807 units over the last five years to 25,340 houses.
In December 2010, there were 27,147 houses listed as DCC social housing units.
The decrease can be accounted for in a number of ways. Council tenants were entitled to apply to buy their homes under a scheme which was closed in 2012 - however, some of these sales may not have been completed by then.
Other units may have been transferred to voluntary housing bodies or other organisations who provide social housing.
Mr McGinley said that the figures were worrying, as the demand for social housing continues to increase.
He said that "it's not rocket science" for the Government to solve the housing crisis by building more houses.
"The decrease means that the council's ability to directly respond to the housing demand lessens, and there is also less rental income.
"The upside, if there is one, is that the council spends less on maintenance costs for its housing stock," he said.
Meanwhile, the council has purchased just 125 houses so far this year.
The figures come as the city council is due to hold a special meeting on Thursday to allow members to debate Sinn Fein's motion calling on Environment Minister Alan Kelly to exclude Dublin from the new tenant purchase scheme.
The scheme will come into effect in January and will allow tenants to once again apply to buy their homes, in some cases at a discount.
However, Sinn Fein want Dublin to be exempt until the council is in a position to meet the demand for housing.
The move has caused some discontent among members, with Fianna Fail calling on the public to lobby their councillors to reject it.