In order to communicate well in a foreign language; students should know a sufficient number of words and be familiar with how to use them correctly. However, this endless amount of words may discourage many students who do not know how to memorize the number of vocabularies rapidly. As many foreign language learners, especially ESP learners, have problem in memorizing the vocabulary items and are not aware of the existing vocabulary-learning methods, this study, by comparing two teaching methods, i.e. keyword method and word-list method, provides beneficial information for students, teachers, curriculum designers and researchers.