Friendships are key to reducing stress and improving morale and social support. Loss of friendships after a traumatic brain injury (TBI) can have a significant impact on these areas of a person’s life. There is little in the research literature on the quality of friendships between people with TBI and their friends. This study aimed to address this gap in knowledge by measuring the relationships between 18 adults with TBI and their nominated (non-family member) friends and compare this to 18 matched adults without a TBI and their nominated friends. The researchers measured the participants’ social participation and friendship quantity, and the participants and their nominated friends’ friendship quality (using a questionnaire). They then compared the results between the TBI group and the non-TBI group. Results demonstrated significantly reduced social participation on the part of the TBI group. However, there was no significant difference in the number of friends and the quality of these relationships, although the informant friends of participants with TBI did report less affection for their friend with a TBI and there were two participants with TBI who were unable to nominate a friend. This study highlights that where rehabilitation focuses on social support, this work could benefit from working on social activities and frequency of interaction to increase an individual’s exposure to potential friendships. Maintaining a high quality of life following an injury is a valuable protective mechanism for long-term physical and mental health and thus should be a priority for rehabilitation services.