BackgroundFemale general practitioners (GPs) have higher chlamydia testing rates than male GPs, yet it is unclear whether this is due to lack of knowledge among male GPs or because female GPs consult and test more female patients.MethodsGPs completed a survey about their demographic details and knowledge about genital chlamydia. Chlamydia testing and consultation data for patients aged 16-29 years were extracted from the medical records software for each GP and linked to their survey responses. Chi-square tests were used to determine differences in a GP’s knowledge and demographics. Two multivariable models that adjusted for the gender of the patient were used to investigate associations between a GP and their chlamydia testing rates ― Model 1 included GPs’ characteristics such as age and gender, Model 2 excluded these characteristics to specifically examine any associations with knowledge.ResultsFemale GPs were more likely than male GPs to know when to re-test a patient after a negative chlamydia test (18.8% versus 9.7%, p = 0.01), the correct symptoms suggestive of PID (80.5% versus 67.8%, p = 0.01) and the correct tests for diagnosing PID (57.1% versus 42.6%, p = 0.01). Female GPs tested 6.5% of patients, while male GPs tested 2.2% (p < 0.01). Model 1 found factors associated with chlamydia testing were being a female GP (OR = 2.5, 95% CI: 1.9, 3.3) and working in a metropolitan clinic (OR = 3.2; 95% CI: 2.4, 4.3). Model 2 showed that chlamydia testing increased as knowledge of testing guidelines improved (3-5 correct answers – AOR = 2.0, 95% CI: 1.0, 4.2; 6+ correct answers – AOR = 2.9, 95% CI: 1.4, 6.2).ConclusionsHigher rates of chlamydia testing are strongly associated with GPs who are female, based in a metropolitan clinic and among those with more knowledge of the recommended guidelines. Improving chlamydia knowledge among male GPs may increase chlamydia testing.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-014-0584-2) contains supplementary material, which is available to authorized users.