Omagh High School
Principal Christos Gaitatzis and his staff at Omagh High School were "absolutely delighted" with their results.
Student Kirsty Clarke (16) said she was "happy enough" with her four As and five Bs.
"I think the grades were fair enough and for me they pretty much match up with what I had been expecting," she said.
Kirsty is now turning her attention to picking her A-level subjects - childcare, geography and literature - with a view towards a career in teaching.
"I was worried but it was definitely a relief when we learned that we would be getting our teacher's grades because they know us better than anyone," Kirsty added.
Fellow pupil Evan Buchanan (16) was "over the moon" with his A* in science, As in agriculture, geography, maths and remaining Bs and Cs.
"I'm shocked but very happy as I didn't think I would do as well as this even though I had a feeling I'd be alright.
"I was a bit worried on Thursday about being downgraded but realised at that stage there wouldn't be too much I could do about it," Evan said.
"My teachers have taught me for the past five years so I knew that they would be fully aware of what I was capable of."
Praising his students, Mr Gaitatzis added: "It is extremely rewarding to see the progress made by all our pupils in fulfilling their true potential - the culmination of two years of hard work, long hours studying and anxious hours revising.
"In all 90% of our students achieved 5 GCSE A* to C an exceptional performance that clearly indicates the passion of our teaching staff and the hard work of our pupils."