A range of discourse analyses are effective in identifying features which are aberrant following traumatic brain injury (TBI). We examined the exchanges of five traumatically brain-injured subjects and five matched controls across four speaking situations which included speaking to a therapist, to the bus timetable information service, to the police, and to their mothers on the telephone. Transcripts were analysed using the exchange structure analysis of systemic functional grammar. This analysis provided an indication of information giving (K1 moves per minute); information requesting and receiving (K2 moves per minute) and the amount of negotiation that was needed for the messages to be conveyed (dynamic moves per minute). Results indicated that the TBI subjects performed differently across the four conditions, and were differentiated from the matched controls on a number of measures. The role of different communication partners is also addressed. Communication partners were noted to interact differently with TBI subjects when compared with controls. This included increased information giving to control subjects; more requests for information by police from TBI subjects and a greater use of dynamic moves by therapists with controls. The potential of exchange structure analysis is discussed as a useful way of examining the discourse of TBI subjects and their communication partners. Exchange structure analysis highlighted the dynamic nature of information exchange and the subtle ways speakers responded to familiarity and power imbalance in social interaction. This study has implications for family and community education regarding communication with people with TBI.