Some 54,000 students learned the results of their Australian Tertiary Admission Rank (ATAR) on Thursday, with the average ranking showing a slight improvement on last year.

It comes after some HSC subject results were leaked over the weekend, when students were briefly able to access their results online through a student portal.

The incident is being investigated by the NSW Education Standards Authority.

The results showed 29 boys and 19 girls received the highest possible ATAR of 99.95, with the top students from a mix of public and private schools.

Nearly one-fifth of students achieved a score of 90 or higher, just over one-third received a score of 80 or higher, while just over half scored at least 70.

The average ATAR was 71.25, a slight improvement on the previous year. The average for girls was 72.45, while the average for boys was 69.85.

NSW Education Minister Sarah Mitchell said the class of 2022 had a bright future and students were now highly likely to be engaged with work or training after leaving school.

Three-quarters of students were involved in training or educations and another 20 per cent were employed, a recent report from the NSW government showed.

"My message to all those who received their HSC results today is to take all that you have learnt and the resilience and determination you have shown over your final years of school into whatever it is you choose to do next, whether that be university, training or work," she said.

Kim Paino, from the Universities Admissions Centre, said many students would still be made offers for university placements, even if they achieved a result lower than their lowest selection rank.

"Remember, too, that many students don't go straight into their first preference in their first year of tertiary study, and instead start in a general degree and apply to transfer after a year of study," she said.

About 15,000 students have already received an early university offer, but will be eligible for second-round offers this month.

Australian Associated Press