Language impairment in brain tumour patients may be missed since standardised tests fail tocapture mild deficits. Neuroplasticity may also contribute to minimising languageimpairments. To address this possibility, we examined 14 patients with language dominanthemipsheric brain tumours prior to their first surgery using magnetoencephalography (MEG)imaging while they performed a demanding picture-word interference task. During picture-word interference, participants name pictures while ignoring distractor words. Brain tumourpatients had the behavioural picture naming effects typically observed in healthy controls. Bycontrast, the MEG event-related effect had a right hemisphere source, in contrast to the classicleft hemisphere source found in healthy individuals. This finding supports tumour inducedneural reorganisation of language prior to surgery. We also identified one participant with alesion affecting the left temporal lobe and underlying white-matter tracts who showed adeviant pattern in behaviour as well as in the MEG event-related responses. Our resultsprovide support for neuroplasticity of language in brain tumours in the pre-surgical phase.