The Cook Islands is ranked as the second worst country in the Pacific for chlamydia infection rates among people younger than 25 years.
Ministry of Health figures show almost half of the Cook Islands' youth population is infected with chlamydia.
A 2009 survey of Cook Islanders aged between 15 and 19 years found 49 percent of the teenagers tested were infected with the sexually transmitted disease.
Samoa has the highest rate of chlamydia infection in the South Pacific according to survey data which shows 41 percent of its test subjects were infected.
The figures have been disclosed at the Cook Islands' annual health conference in Rarotonga.