Mild traumatic brain injury (TBI) is common and can result in symptoms that persist for years after the initial injury. The symptoms following TBI are dynamic, and can result in cognitive, emotional, behavioural and physical symptoms, often collectively referred to as post-concussion symptoms. Persistent post-concussion symptoms impact education, employment, relationships and quality of life. The first aim of this study was to evaluate the long-term symptoms of adults eight- years after a mild TBI compared to a TBI-free group. The second aim of this study was to compare the prevalence and severity of post-concussion symptoms that were reported at 1-month post-injury, 12-months post-injury, and the symptoms reported now, at 8 years post-injury. Finally, the factors contributing to subjective cognitive complaints at 8-years post-injury were explored. A population-based sample of 151 adults who sustained a mild TBI (mTBI) between 2010 and 2011 participated in this study. Additionally, 213 participants with no history of head injury took part. Both groups answered questions about current post-concussion symptoms using the Rivermead Post-Concussion Symptom Questionnaire (RPQ). The results of this study revealed the prevalence and severity of post- concussion symptoms was significantly greater in participants with mTBI at 8- years post-injury. Differences in cognitive symptoms were most prominent between groups, with the mTBI participants reporting significantly more cognitive complaints. When evaluating symptom-severity over time, we found no significant change in post-concussion symptoms from 12-months post-injury to 8-years. Older age at injury and increased symptoms of depression were associated with increased cognitive complaints at 8-years post-injury. These results confirm post-concussion symptoms persist long-term, and may not improve beyond the levels reported at 12-months post-injury. Further research is needed to explore the impact that treatment of mood symptoms early post- injury may have on recovery.