Studies conducted around the world have shown that the structures of various languages have shifted over time towards that of English. This phenomenon could be attributed to the use of English as a lingua franca or to these languages’ contact with English via translation. This thesis investigates this shift towards English-language structure in translated and original Arabic scientific texts. To this end, I developed a diachronic corpus for scientific articles dating between 1997-2000 and 2016-2018 to generate findings for this genre. The study used both parallel and comparable corpora, allowing an investigation of the influence of English not only on translated texts but also on original scientific texts written within the same time frame. The results reveal that the English language has affected the Arabic passive voice structure in translated scientific texts, and that the English passive voice structure seems also to have affected original modern Arabic scientific texts. As for the agentive passive, English does not seem to have increased its influence between 1997-2000 and 2016-18 in the translated texts as most agentive English passives are translated into active Arabic sentences in both the 1997- 2000 and 2016-18 corpora. There also does not seem to be a significant increase in the agentive passive in original texts between 1997-2000 and 2016-2018
