School principals have blamed an "uneven distribution" of graduate teachers across the country for the increasing number of retired teachers being re-employed as substitutes.
According to figures supplied to Fianna Fáil Education Spokesperson Charlie McConalogue by the Minister for Education, there were 153 retired teachers on the teaching payroll in December.
Most of these retired teachers were working in a substitute capacity.
Mr McConalogue described the situation as extremely "wasteful" at a time when many graduate teachers cannot find work.
Speaking on RTÉ's Morning Ireland, Deputy President of the Irish Primary Principals' Network Brendan McCabe said IPPN would always recommend that principals employ young graduates as substitutes rather than retired teachers, by preference.
However, he said this was not always possible because of the "very uneven distribution" of available teachers throughout the country at the moment.
He said the IPPN operates a system called "Text a Sub" through which teachers looking for work can register county by county and principals who need teachers can send texts to every unemployed teacher in the area.
Mr McCabe said it was his own experience that this system had worked very well and he had got a substitute teacher within hours, but other times no-one had responded to the texts.
He said, for example, there were 46 teachers registered on "Text a Sub" in Galway, where there were 270 schools.