The proportion of GCSE exams in Northern Ireland awarded an A* grade has risen to almost a tenth.
Performance in English, maths and science improved, according to the organisation which oversees qualifications.
Three quarters of entrants achieved grades A* to C. There was an improved showing from boys, but girls maintained the gender gap.
Anne Marie Duffy, a representative of the Joint Council for Qualifications which published the results, said the figures showed continued high performance.
“It is pleasing to see the hard work of Northern Ireland students and teachers being reflected in these results.
“The performance in core subjects of English and mathematics will provide strong foundations for learners as they move on to further education, training and employment.
“There were also notable performances in modern languages, science subjects and music.”
This summer there has been a 0.2% increase in the proportion of entries awarded the top A* grade, rising to 8.9%. Entries achieving A* to A have also seen an increase, rising 0.2% to 28.2%. The performance of pupils at A* to C has risen by 1.5% to 78% of entries.
More detailed analysis of the data shows increased achievement in English, maths and science.
In summer 2014 the percentage of entries achieving grades A* to C in English rose from 68.8% in 2013 to 73.0%. In maths the percentage gaining these grades rose 1.6% to 66.2%, and in science from 61.5% in 2013 to 64.8%.
The individual sciences saw particularly high performance. The proportion of entries awarded A* to C in biology sits at 93.3% (91.2% in 2013), in chemistry 93.6% (93.4% in 2013) and in physics 95.0% (94.7% % in 2013).
There were also notable performances in music and modern languages. The proportion of entries awarded A* to C in French was 85.5%, German 86.1%, Irish 95.5% and Spanish 91.4%. The corresponding figure for music was 91.5%.
This summer saw an increased percentage of entries from boys achieving the A*, A* to A, and A* to C grades. Despite this improvement, girls maintained the gap in performance outperforming boys by 4.3% points at A*, by 10% points at A* to A, and by 7.6% points at A* to C.
The number of overall entries was down by 2% to 172,692 but science, technology, engineering and mathematics subjects maintained their popularity, according to the qualifications body.
Despite this, there were notable increases in additional mathematics, business studies, German, ICT, mathematics, and statistics.
The popularity of Stem subjects such as biology, chemistry, design and technology and physics has been maintained. This is also the case for modern language subjects.