Foreign patients receiving medical treatment in Rotorua owe more than $110,000 in unpaid bills, with some skipping the country without paying.
Some of the debt is likely to be written off, meaning less funding for local health services.
According to figures released to the Rotorua Daily Post under the Official Information Act, five foreign patients treated locally owed Rotorua health authorities a combined total of $83,796 in unpaid bills for the six months to December 31.
In addition, $24,133 was still outstanding from the treatment of eight foreign patients in the year to June 30, 2013; $4377 was owing from a single foreign patient in the 2011/12 financial year; and $2803 was owing from three foreign patients in the 2010/11 financial year.
The biggest single debt owed locally by a foreign patient in the past three years came to $24,954.
Lakes District Health Board chief executive Ron Dunham said the number of foreign patients seeking treatment spiked during summer because of higher tourist numbers.
"Anecdotally, there were increases in all outdoor activities, in particular more water skiing-related injuries," Mr Dunham said.
While the board used debt collection agencies to chase what was owed, about 10 per cent of the debts had to be written off. "Any monies written off means less funding available for provision of services," Mr Dunham said.
Mr Dunham said information on foreign patients' conditions was not kept and there was "no country dominant" in the Lakes DHB debt figures.
New Zealand has a reciprocal free health care arrangement with residents of Australia and the UK, plus citizens of Tokelau, Niue and the Cook Islands.
Foreigners who have accidents are covered by ACC.
A Ministry of Health spokesman said: "The debts are chased up by the individual DHBs and, if they can't recover them after all reasonable steps, they will be written off by the DHB." DHBs can also contract debt collection agencies to chase up outstanding medical bills.