In this paper, we tested 20 Brazilian Portuguese speakers at intermediate and ad- vanced English proficiency levels to inves- tigate the influence of Google Translate’s MT system on the mental processing of English as a second language. To this end, we employed a syntactic priming experi- mental paradigm using a pretest-priming design which allowed us to compare par- ticipants’ linguistic behaviour before and after a translation task using Google Trans- late. Results show that, after performing a translation task with Google Translate, participants more frequently described im- ages in English using the syntactic alter- native previously seen in the output of Google Translate, compared to the transla- tion task with no prior influence of the MT output. Results also show that this syntac- tic priming effect is modulated by English proficiency levels.