The successful CaddyShack pop-up chlamydia screening unit will visit Shellharbour Beach on Tuesday, Kiama Surf Beach on Friday, Mollymook Beach on January 24 and North Gong Beach on January 30.

The project is targeting those aged 15 to 24, who have the highest rates of sexually transmitted infections (STIs) in NSW with chlamydia the most common.

There were more than 82,000 chlamydia notifications in Australia in 2012, and it's a major issue in the Illawarra where there has been a 20 per cent increase in notifications in the past four years.

Healthy Cities Illawarra health promotion officer Nadia Sneyd-Miller said the CaddyShack screening project, run in partnership with the Illawarra Shoalhaven Local Health District, aims to raise awareness of sexual health among young people.

"By running this engaging project at the region's beaches, we aim to debunk the stigma and discrimination around STIs and encourage young people to get tested," she said.

"By taking testing to where young people hang out, it's a free, easy and accessible option for those who may not feel comfortable going to their family GP or medical centre."

Participants undergo a simple urine test and if the results are negative for an STI, they will receive an SMS with the result within 10 days. If they test positive, then a sexual health counsellor will contact them to discuss their options.

The Kirby Institute has estimated as many as one in 20 young Australians have chlamydia, most of them going undiagnosed.

"Chlamydia is known as the 'silent STI' because there are often no signs or symptoms," Ms Sneyd-Miller said.

"But if left untreated, it may lead to pelvic inflammatory disease and infertility."