The paper focuses on the use of prepositions by students of English as a Foreign Language (EFL) at Ho Chi Minh City University of Food Industry, Vietnam, adopting a cognitive linguistics and conceptual metaphor theory perspective. 141 students randomly selected from different faculties and one institute at the above mentioned university took part in the survey. This involved a questionnaire including 70 multiple-choice items and 5 writing tasks, in which the students were required to fill in the blanks with the prepositions they deemed appropriate. Results suggest that geographical factors, attitude to colours, and negative transfer affect the choice of prepositions, differently from other factors such as gender, reading habits and leisure/outdoor activities. The authors conclude that prepositions are more challenging than other parts of speech for EFL students. They suggest that EFL teachers take into account non-linguistic factors when teaching the use of prepositions, which may be associated with different metaphor schema images depending on the context in which they appear. They also stress the positive effects of a cognitive linguistics-based approach to the teaching of prepositions, to help students improve their understanding of the metaphorical meanings of prepositions.