PURPOSE OF THE STUDY The aim of our study is to show the pitfalls of performing skull X-rays in patients with head injuries and the lack of accuracy of this examination nowadays, and to clarify the current trend in the MTBI investigation algorithm. MATERIAL AND METHODS A retrospective study of 3,950 patients treated for acute head injury at the Department of Trauma Surgery (University Hospital Brno) in the period from 2015 to 2016. Inclusion criteria were the following: mild brain injury (GCS = 15), primary skull X-ray design in head injury diagnosis. Patients with a positive skull X-ray finding underwent a head CT evaluation up to 24-hours from the injury except for the patients with an isolated nose bone fracture. A CT head scan was also performed in patients indicated by the neurologist at the initial examination based on the anamnestic data and an objective finding. RESULTS Inclusion criteria were met by 1,938 patients. In 1806 (93.2%) cases the X-ray was negative, in 132 (6.8%) patients the X-ray was positive, of which in 62% of patients a nasal fracture was detected. A skull fracture reported in 16 cases. Once the CT scan of the head was obtained, all of these cases were classified as false negative. After the CT scan of the head, intracranial bleeding was observed in 12 patients, in 4 cases accompanied by fractures of the skull, not visible on the X-ray images. After the statistical evaluation, the sensitivity and specificity of the X-ray examination compared to the CT scan of the head was determined to be 0.00 and 0.94, respectively. DISCUSSION The aim of MTBI diagnostics is primarily to detect serious intracranial lesions requiring neurosurgical intervention. A simple X-ray of the skull shows fractures only and does not allow to visualize both the brain and any traces of bleeding that would show an intracranial injury. Hofman, in his meta-analysis, points out that a simple X-ray image of the skull has only very little noticeable value when diagnosing MTBI. The prevalence of intracerebral hematoma (ICH) over MTBI is 0.083. The sensitivity of a radiographic finding of skull fracture in the diagnosis of ICH based on the CT verification is only 0.38 with a specificity of 0.95, which is consistent with our study where the sensitivity of the radiographic finding was 0.00 with a specificity of 0.94 relative to CT. Thus, the question is not whether to perform an X-ray of the skull in mild head injuries, but rather when to indicate a CT scan of the brain, when to admit the patient to the hospital for observation, and for how long or when the patient can be safely discharged into home care. The purpose of MTBI diagnostics, however, should not be a rashly decision to perform a brain CT scan, but to put into practice the CT indication criteria in MTBI applying and respecting the validated guidelines known worldwide. CONCLUSIONS Our study, in which no X-ray examination revealed possible intracranial bleeding, clearly shows that nowadays the plain radiograph of the skull does not bring any benefit in the diagnosis of minor traumatic brain injury. Key words:skull X-ray, CT of the head, head injury, minor traumatic brain injury.