In an earlier historical cohort study on the post-concussion syndrome (PCS) in Lithuania, a country in which there are few confounding factors, the validity of this condition as a disease entity could not be confirmed. In order to register the post-traumatic symptoms, the influence of sociodemographic factors, and the effect of expectation on these symptoms more reliably, we performed a controlled prospective study. Three hundred subjects with concussion were followed up with repeated questionnaires for 1 year. For each study subject, a sex- and age-matched control person with minor non-head injury was identified. These controls received similar questionnaires. Headache both after 3 months and after 1 year did not differ significantly between the head-injured participants and the non-head-injured controls. Several other symptoms attributed to PCS did not differ significantly between the groups after 3 months. After 1 year the vast majority of symptoms did not differ significantly. Exceptions were slightly significant differences concerning memory problems, concentration problems, dizziness and tiredness. These differences were insignificant when analysing symptoms in unmarried and/or people with lower education, separately. No relationship between cognitive dysfunction and the severity of concussion was found. Although the possibility of a mild organic brain injury cannot be completely ruled out, our results cast doubt on the validity of PCS as a useful clinical entity, at least for head injuries with loss of consciousness for <15 min. Sociodemographic factors and expectation seem to influence reporting of symptoms after concussion.