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.
Sixty-eight per cent of positive cases were for people aged 15-24, and 50 per cent of cases were diagnosed in non-European patients, including Maori and Pacific people.
But there were also 84 cases where children under 12 months old had been diagnosed with the disease after contracting it during childbirth from mothers who were infected.
The report that the decrease in the estimated national rate should be taken with caution, as more DHBs provided information and the report had decided to exclude repeat tests for individuals.
In total, there were 28,316 positive tests across all district health boards, with the highest rates being reported in Tarawhiti, Lakes and Hawke's Bay.
Sexually transmitted infections - other than AIDS - are non-notifiable so the report relies on laboratories voluntarily providing information.