Background: Head injury is a common traumatic condition seen in Kenya. Among the head injury patients seen at the Aga Khan University Hospital Nairobi, minor head injury patients are the highest proportion of non–fatal trauma patients. Minor head injury is described as witnessed loss on consciousness, definite amnesia or witnessed disorientation in a patient with a GCS score of 13–15 who has suffered a traumatic event. There has been considerable disagreement about the indication for a Computed Axial Tomography Scan of the Head (CT-head) in the large number of patients clinically classified as minor. The Canadian CT Head Rule was derived as a sensitive decision rule on the use of CT with the aim to standardize and improve the management of patients with minor head injury. The rule comprised of five high risk factors and two moderate risk factors(Appendix 1). At the Aga Khan University Hospital Nairobi, there are no protocols that guide the decision making by physicians on when to do a CT-head for patients who have suffered a minor head injury. According to a pilot study done, approximately 96% of patients with minor head injury have a CT–head done. Objective: To determine the change in proportion of CT-scan done in patients with minor head injury after introduction of the Canadian CT Head Rule Guide at the Aga Khan University Hospital Nairobi. Secondary objectives were to determine the proportion of patients with minor head injury and moderate risk factors according to the Canadian CT Head rule for whom CT was ordered, probability of neurosurgical intervention in patients with minor head injury and their outcomes on follow up. Study design: A Before - After study Method: A total of 84 eligible patients diagnosed with minor head injury were recruited at the Accident and Emergency Department. Forty - two patients were assessed and data on high risk factors and moderate risk factors of the CCHR, Glasgow coma scale, age, management plan and the Glasgow outcome score on follow-up collected with data collection form 1 (see appendix 2) in the 'before' group, thereafter the Canadian CT Head Rule (CCHR) was introduced and another forty-two patients were assessed according to data collection form 2 (see appendix 3). Results: The proportions of CT scans done in the 'before' and 'after' groups were 95.2% and 21.4% respectively. The difference of 73.8% between the two groups was statistically significant (CI 0.55 to 0.84).The proportion of patients