Since the University Grants Committee (UGC) selected the academic module of the International English Language Testing System (IELTS) as the common English proficiency assessment for graduating undergraduate degree students in 2002, almost all the tertiary institutions in Hong Kong have offered IELTS preparation courses that aim at providing students training in IELTS taking strategies and giving them practice with IELTS tasks under exam conditions. This study examines the potential impact of IELTS preparation course on IELTS test performance. A web-based questionnaire designed to collect information about students' IELTS preparation experience and performance was distributed to the students who had applied to take the common English proficiency assessment in the 2003/2004 academic year in one university in Hong Kong. The findings showed no significant differences in exit IELTS test scores between students who had taken an IELTS preparation course prior to the test and those who had not taken such a preparation course. However, significant differences were found between the two groups in their university entrance English exam scores. Our findings indicate that students who scored lower in the university entrance exam were more likely to take the later test preparation course prior to the exit IELTS test. The lack of statistically significant differences between the two groups in the exit IELTS test scores also points to the fact that the gap in English language proficiency between the two groups reflected in the entrance exam scores appeared to have narrowed by the time they took the exit test, which is apparently the result of the university English learning experiences, of which participation in IELTS preparation courses should be an important part. Implications for the issue of "homogenous IELTS scores" in Hong Kong, as well as the learning/motivational effects of IELTS preparation courses are discussed. (Contains 6 tables.)