The purpose of guidelines is to reduce practice variability, but they need to be evidence-based. We examine current mild traumatic brain injury guidelines, critique their basis in evidence and examine their variability in recommendations. A systematic search of the literature found 38,806 abstracts, with 41 guidelines. There were 18 sports-related guidelines, 13 related to admission policies, 12 related to imaging and 5 related to neuropsychological assessment. Some guidelines addressed several areas. Only 5 guidelines reported a methodology for the assembly of evidence used to develop the guideline. After appraising the guidelines against a validated index, we found that 3 of the 41 guidelines could be categorized as evidence-based. Two of these focused on paediatric patients and 1 on adult patients. Limited methodological quality in the current guidelines results in conflicting recommendations amongst them.