According to GNAT, it was unacceptable because the country had invested so much in the training of the teachers and yet, they were not recruited despite the many empty classrooms across the country.
It has, however, called for a national dialogue of stakeholders to find a solution to the mass failure of prospective teachers in the Ghana Teacher Licensure Examination (GTLE).
Thomas Musah, the General Secretary of GNAT, described the failure of the teachers as a "financial loss to the state" given the huge investment made in them, since without the license, there was no way they could teach in the country.
In an interview with Daily Graphic, he said "I think this should be a wake-up call for all of us and there is the need for a national dialogue.
"This is for the National Teaching Council (NTC) to present this particular results for the stakeholders to interrogate."
Out of the 7,728 prospective teachers who sat for the licensure examination in May this year, only 1,277 passed.
This means 6,481 teachers failed.
The figure represents 16.5 percent of the candidates who sat again for the examination, introduced to licensed teaching practitioners.
The Registrar of the Ghana Teacher Licensure Examination (GTLE), Dr. Christian Addai-Poku, said all the candidates had sat for the exam at least twice, with some sitting as many as nine times.
He explained that those affected had one more chance to re-write the exam in the latter part of the year before its format and content changed.
He said candidates who would fail at their last chance and would want to continue to resit the exam, would be those with first degree.