Immigration New Zealand figures show there are now fewer than 50,000 foreign students in the country.
In mid-March, there were 60,348 students with valid visas in New Zealand, but by early August that had fallen to 47,807.
The figures indicate polytechnics and private training institutes had lost about a quarter of their foreign students since March, while schools and universities had lost a fifth of their students.
No foreign students had been allowed into New Zealand since the borders closed to non-residents on 19 March and students from China were stopped at the start of February.
However, Immigration New Zealand approved 582 new study visas in June and 633 in July.
It said the visas were for people who were already in New Zealand and might include people who were eligible to study here as dependents of somebody with a work visa.
It said 272 of the 633 applications in July were for fee-paying international students.
The figures showed there were 7943 foreign students at polytechnics on 9 August, 9879 at private training establishments, 9713 at schools, and 17,081 at universities. A further 3191 students' locations were not recorded.
A further 6149 people outside New Zealand had valid study visas, including 3426 for universities and 1362 for schools.