The Secretariat of the Pacific Community says Pacific Island countries are making good progress beating sexually transmitted diseases like chlamydia.
But the regional development body says in some countries as many as one in two young people have the infection which can lead to serious health problems like HIV.
The SPC says Nauru and the Cook Islands have had considerable success.
In Nauru mass treatment coupled with community awareness has led to a drop in the rates of chlamydia from nearly half of pregnant women with the disease three years ago to just four percent this year.
The Cook Islands' rates for pregnant women have halved over the same period.
The secretariat says it has trained more than two hundred health workers and volunteers this year to prevent HIV and sexually transmitted diseases around the region.