Introduction The current Australian National Cervical Screening Program involves regular screening of sexually active women ≥18 years using a Pap test but changes to the program, effective in 2017, will only include women aged ≥25 years. These changes could inadvertently reduce chlamydia screening which is recommended in 15–29 year-olds and often occurs during reproductive visits. Using the ACCESS surveillance system we measured the proportion of chlamydia tests that may no longer occur in primary care following changes to the National Cervical Screening Program. Methods Consultation, Pap and chlamydia testing data were extracted from patient management systems of 18 general practice and family planning clinics in Victoria and NSW. We calculated concurrent Pap and chlamydia testing (within 7 days) by age group, and chlamydia testing frequency among concurrent testers. Results Between January 2009 and September 2014, 10,105 chlamydia tests were conducted among 44,694 women aged 18–30 years; 63% in 18–24 year-olds and 37% in 25–30 year-olds. In the same period, 10,178 Pap tests were conducted; 47% in 18–24 year-olds and 53% in 25–30 year-olds. The proportion of chlamydia tests conducted concurrently with a Pap test was 20% (2058/10,105), similar in both age groups. For 63% (1154/1835) of women with concurrent chlamydia/Pap tests it was their only chlamydia test during the study period. Conclusion One in five chlamydia tests among 18–30 year-olds occurred concurrently with a Pap test and the majority of them had no other chlamydia test during the study period. Our results suggest changes to the National Cervical Screening Program could reduce opportunistic chlamydia testing in a particularly high risk group such as sexually active women aged 18–24 years. As chlamydia is mostly asymptomatic, regular and opportunistic screening is considered a key public health strategy in chlamydia control. New strategies will be needed to increase chlamydia testing in young women. Disclosure of interest statement None.