An Education Review Office report has found holes in the way overseas students are cared for in the billion-dollar export education system.
Most of the schools investigated were meeting their obligations in looking after international homestay students, the report says.
But several were failing to provide the required welfare andaccommodation.
Chief among concerns were the lack of procedures to act when students were "unable to protect themselves against significant harm" and the availability of a designated person responsible for pastoral care.
A code of practice for the care of international students was introduced two years ago.
ERO chief review officer Karen Sewell said many of the schools reviewed were providing high-quality care.
But not all were meeting the code's requirements.
"It is the responsibility of all schools that enrol international students to review their practices and provide the quality of care to which these students are entitled," said Ms Sewell.
Pastoral care of international students has been identified by many in the export education industry as one of the most critical to its long-term success.
But in the rush for a quick dollar, some in the industry have been tempted to treat young foreigners as an easy cash cow.
An ERO report released last July found conflicts of interest at a small number of schools involving foreign fee-paying students and a member of staff or the board.
An investigation into similar allegations is under way at Cambridge High School in the Waikato.
The latest report follows a five-month investigation into 30 secondary schools' compliance with the code.
ERO found that seven of the schools were failing to meet the code's welfare requirements, and nine were not up to scratch in accommodation provision.
A further report into more schools with international students will be completed next year.
