Aim In assessing patients with headaches, general practitioners (GPs) play an important role in determining which patients require computed tomography (CT) scans. The purpose of this study was to identify factors that influence GPs' decisions to refer CT scans for patients with headaches. Materials and methods A self-administered survey was presented to GPs in Western Australia. One hundred and twenty-eight vignettes describing patients who may have required CT referral for headache were constructed encompassing six clinical variables. Nine vignettes, selected at random, were presented to each respondent. Respondents were asked if they would refer the patient for diagnostic imaging tests, if so, which imaging modalities would they request, how urgently and the perceived benefits of the requested imaging modality. Multinomial logistic regression was used for the multivariate analysis. Results We received 105 completed questionnaires (21%). GPs were more likely to refer patients with headaches for diagnostic imaging and CT scans in the following clinical scenarios: patients with a history of colorectal cancer and epilepsy; and patients feeling unwell for the past 6 weeks and headache being exacerbated with valsalva manoeuvrers. Private health insurance and other respondent demographics such as GPs experience and site of care increased imaging referral. Conclusion GP's referral decisions of diagnostic imaging and CT examinations for patients with headaches are dependent on clinical scenarios and the likelihood of a significant pathology. Further research is required to identify the significant clinical findings with regard to the CT referrals and ensure that CT scans are not requested in patients who are unlikely to benefit.