The pedagogical value of authentic materials and learners' positive attitudes toward such materials stand opposed to adapted materials, which lend themselves easily to language learning. Our research question focuses on the effect of authentic text adaptation on vocabulary retention among university-level students of Maritime English. Our study aims to answer the question of whether learners are more likely to retain new lexis when it is presented in adapted texts as opposed to authentic texts. The written instrument, in the form of a questionnaire, was administered in three separate parts: the Pre-test, which served to test participants' prior knowledge of the target vocabulary; the Main Text, a reading text administered in either authentic (Auth) or adapted (Adapt) version (with text adaptation following the Borucinsky and Jelčić Čolakovac's [2020] methodological steps); and the Post-test in the form of a cloze-type task, which tested students' vocabulary retention. Our results showed that retention performance was higher with the Adapt text than with the Auth text (p <.001). The Adapt text provided participants with a simplified context, making it easier for them to memorize the tested vocabulary and apply it in a new context with higher accuracy.