We conducted a chlamydia prevalence study from January to June 2009 among a community sample of young international backpackers by recruiting at hostels in Sydney, Australia. Participants completed a questionnaire; men provided a urine sample and women provided a self-collected vaginal swab, which were tested for Chlamydia trachomatis DNA by strand displacement amplification. We recruited 225 men (median age 24 years) and 207 women (median age 23 years). Most (87%) of the travellers came from Europe. A new sexual partner during travel was reported by 67%, and 51% had more than one new sexual partner. Of those reporting a new sexual partner, 40% always used condoms. Prevalence of chlamydia was 3.5% (3.1% in men, 3.9% in women). Previous testing for chlamydia was reported by 40%. Drinking alcohol at hazardous levels was reported by 58% of men and 29% of women. Despite the reporting of new sexual partners and inconsistent condom use, the prevalence of chlamydia in these backpackers was not higher than that found in more general populations, and may relate to good health-care seeking behaviour. Young travellers need education about sexual risks and promotion of condom use prior to travel, and access to public sexual health services.