Apathy and reduced self-awareness are frequent occurring neurobehavioural sequelae following traumatic brain injury (TBI). Apathy, in terms of reduced goal directed activity and lowered motivation, and reduced self-awareness have a negative impact on the rehabilitation process. In this study, 30 patients suffering severe TBI were clinically rated for apathy and monitored for cardiovascular and electrodermal reactivity during baseline, neutral speech and therapeutic interaction. Applying a cut-off score criterion, two thirds of the TBI sample were classified as apathetic. The apathetic patients showed less psychophysiological reactivity from neutral speech to therapeutic interaction, compared to non-apathetic patients. They also reported less perceived emotional discomfort in the therapeutic situation measured with a visual analogue scale. Moreover, reduced self-awareness was associated with low autonomic reactivity. The results suggest that the reduced psychophysiological reactivity in apathetic patients may be a correlate to the lack of emotional responsivity, disengagement, lack of insight and concern about their own situation. Clinically, these results may have implications for psychotherapeutic intervention aimed at improving self-awareness. Recording psychophysiological responses during therapeutic interaction may serve as a method for monitoring emotional involvement during psychotherapy with TBI patients.