The aim of this study is to investigate the look-up behaviour of bilingualised dictionaries of Hong Kong students. It focuses on the frequency of use of dictionary information and how useful such information is perceived. Comparison has also been made between students more proficient in English vocabulary and those less proficient to identify the dictionary look-up behaviour which may enhance L2 vocabulary learning. The subjects under study included more than 1,000 students who had just been admitted to the 7 tertiary institutions of Hong Kong. The instrument for data collection comprised a questionnaire and the Word Levels Test. Data were analysed using f-test, multiple comparison, t-test and correlation analysis. Findings of the study indicate that focusing on the Chinese equivalents of English words, students in general make very limited use of the bilingualised dictionary, especially the information related to the speech habit and the social and cultural life of the L2 speakers, such as collocation and appropriateness. The more proficient students, however, make fuller use of the bilingualised dictionary. Implications of these and other findings are discussed and suggestions are made regarding the teaching of dictionary skills in EAP courses.