Chlamydia rates in Kiwis are on the decline, but New Zealand still has a much higher rate of infection than Australia.
Chlamydia was New Zealand's most commonly reported sexually transmitted infection last year, with an estimated national rate of 633 cases per 100,000 people.
That's down from 2012's rate of 744 cases per 100,000, but still much higher than Australia's 2012 rate of 335 per 100,000.
A report by NZ's Institute of Environmental Science and Research has assessed data from laboratories around the country and found the most likely to test positive were 15 to 19-year-old women, with a rate of 5064 per 100,000.
Chlamydia is asymptomatic in 70 per cent of female cases.