A detailed language assessment was conducted with MM, a 17-year-old bilingual teenager with Rasmussen syndrome who had undergone a left functional hemispherectomy. Results revealed important deficits in French and English, affecting expressive and receptive language in both the written and the oral modality. MM's linguistic profile was coherent with previous description of language function following left hemispherectomy, and what is known of the linguistic potential of the right hemisphere (RH). The impairment pattern showed overall similarities between French and English, thus supporting the existence of a common underlying system for these two languages. However, the profiles in each language were not identical, implying that distinct subsystems may also be at play. These findings support previous descriptions of acquired language impairments and recovery in bilingual individuals.