The processes of error awareness and sustained attention were investigated in 18 traumatic brain injury (TBI) individuals and 16 matched control participants. In Experiment 1, we found that: (1) in comparison to controls, TBI participants displayed reduced sustained attention and awareness of error during the Sustained Attention to Response Task; (2) degree of error awareness was strongly correlated with sustained attention capacity, even with severity of injury partialed out; and (3) that error feedback significantly reduced errors. We replicated the finding of a correlation between error awareness and sustained attention capacity in Experiment 2 with a separate sample of 19 TBI participants and 20 controls. We conclude that TBI leads to impaired sustained attention and error awareness. The finding of a significant relationship between these two deficits in TBI suggests there may be a link between these two processes. Feedback on error improves sustained attention performance of control and TBI participants.