The article aims at emphasising the importance of prepositions in language learning and teaching. Identifying the relationship the preposition can establish with other parts and units of speech represent a difficulty for non-native learners of English. During ESP courses, the teacher should focus on examining prepositions in context and explaining the use of prepositions to learners to help them avoid errors in speaking or writing. Due to poor knowledge of the English language or to the mother tongue's influence during the language acquisition process, non-native learners of English might be unaware of the mistakes they make as regards the use of prepositions.