The aim of this study was to determine if an unvalidated imaging guideline can reduce the use of imaging in patients with cervical spine trauma. A non-randomized clinical trial using historical controls was conducted in the emergency department from October 2001 to September 2002. Following an education programme, which introduced the imaging guideline to clinicians, the use of guideline and imaging were measured. The guideline was also converted to decision-support software for use in the emergency department. Three hundred and fifty-three patients satisfied inclusion criteria during the study period and these were compared with 403 historical control subjects. No significant difference was found between the two groups for age, sex or fracture prevalence. A significant increase was observed during the study period in the proportion of patients who were managed without the use of any cervical spine imaging (21.25 vs 31.2%; P=0.03; 95% confidence interval, 3-13). There were no delayed diagnoses of cervical spine injury among those not imaged. It is feasible to disseminate and implement an evidence-based imaging guideline for patients with cervical spine trauma. The use of a computerized decision-support system can facilitate this and is associated with a safe reduction in the proportion of patients imaged.