The compulsory Irish exam for teachers who trained outside the State is finally producing an increasing number of pass grades, after years of a failure rate of over 80 per cent.
Results from the Department of Education's Irish language exam (SCG) show that 83 per cent of primary school teachers passed the aural section last term.
However, while 55 per cent of the 100 candidates passed the oral aspect, 28 per cent failed the second paper and 44 per cent failed the first.
Under current department rules, primary teachers who qualify in Northern Ireland or abroad are given provisional recognition for five years, within which they must pass a State Irish exam to obtain full recognition.
Teacher-training courses abroad have become increasingly popular with Irish students in recent years because of the lower entry points requirement.
Consequently, the numbers taking the Irish exam on return to Ireland has increased from 19 in 1993 to 524 in March of this year.
In the past, teachers have faced dismissal from their schools for failing the exam.
Last year members of the INTO lobbied the union to "actively campaign" for the abolition of the test.
The increase in the number of pass grades awarded to returned graduates in 2005 follows changes in the examination structure and the development of courses by Coláiste Mhuire Marino for teachers to study for the exam, according to John Carr, general secretary of the INTO.
"The results prove that there is nothing intrinsically difficult about the learning of Irish.
"They show that if courses of professional study are made available to those who want to sit the examination, then pass rates will soar, he said.
"The announcement is a vindication of the INTO's position to campaign for support for teachers trained outside the State to learn the language," Mr Carr said.
"The SCG must be passed by a candidate in order to retain a teaching position. For that reason it is a high-stakes test and a very stressful experience.
"Tribute must be paid to the hundreds of teachers who have worked diligently to achieve these results. Credit must also go to their tutors throughout the country for the courses they have provided," he added.