Objective. The study aimed to evaluate the application of ERPs neuromarkers for the assessment and treatment of a patient with chronic crossed aphasia after severe TBI and a long-term coma. Case report. An ambidextrous female patient, aged 29, suffered from posttraumatic chronic crossed aphasia, severe TBI and a prolonged coma after a car accident. The patient took part in two differentiated rehabilitation programmes of neurotherapy included 20 sessions of relative beta training and 20 sessions of rTMS; both programmes were combined with behavioural training. The patient was tested 3 times: before the experiment, after completion of programme A, and after completion of programme B. Results. In the 1st recording, the neuromarker of aphasia was found – an excess of the P2 wave over the left temporal area. There was a cognitive control deficit – an excess of omission errors and an increase of RT variability – all indexes of sporadic ADHD. In the 2nd recording, slight improvements in cognitive control, and language functions were found. In the 3rd recording, after the rTMS sessions most of her cognitive dysfunctions had been resolved, including language functions. It should be stressed that the activation (especially the increase in the ERP potential of the right side over the frontal lobe) was found. The neuromarker of aphasia did not change, only the location had slightly moved frontally. Conclusions. The application of ERP neuromarkers assists in the diagnosis, treatment, and academic success of an ambidextrous patient with chronic posttraumatic aphasia and sporadic ADHD. ERPs can be used to assess the functional brain changes induced by neurotherapeutical programmes.