Five hundred children with special needs were waiting on a school bus place at the start of this academic year.
Figures released to Fianna Fáil show that more than 2,700 applications for school transport for children with special educational needs were accepted for the 2018/19 school year.
However, statistics reveal that transport arrangements were still being finalised for some 500 of these applications at the beginning of September.
Fianna Fáil's Thomas Byrne told RTÉ News he was prompted to ask a Parliamentary Question to the Department of Education following a number of queries from concerned parents with special needs children who were having problems getting a place on the school bus.
Mr Byrne said it was "not fair" that hundreds of children have been left without transport to primary and post-primary schools.
In a statement to RTÉ News, the Department of Education and Skills confirmed that transport arrangements for a number of children with special education needs were still being finalised.
It said that this was due to a '"variety of reasons" including, in some cases, "difficulty in procuring a contractor to transport the child".
The department said that the number of applications currently being finalised was broadly in line with previous years.
It said that the "department continues to work with Bus Éireann to ensure that all eligible children have access to a service and will raise specific issues with Bus Éireann".
However, speaking on RTÉ's Morning Ireland, Mr Byrne said he does not accept the Department's explanation and said there had been an unprecedented number of families contacting his office with queries in recent weeks.