This study investigated the awareness and use of Online Public Access Catalogue (OPAC) by students of Obafemi Awolowo University, Nigeria. A questionnaire was distributed to 800 students at various faculties and in different levels of studies in August 2012. Five hundred and twenty copies of the questionnaire was retrieved and used for the study. The study revealed that 68.7 % of the respondents were aware of the OPAC services; students who were aware of the library OPAC and did not use it to access library resources were statistically significant (x2 =82.073; df =2; α = 0.001); 23.8% of the respondents used OPAC independently; only 3.2% of the respondents accessed library resources from their hostels, 0.2% access it from homes. Similarly, majority of the respondents lacked information searching skills while lack of awareness, irregular power supply, network failure and inadequacy of computer terminals designated for the use of OPAC were among the problems identified as factors inhibiting the use of library OPAC. Therefore, the study concludes that majority of the students used manual catalogues to access library resources due to lack of awareness, skills to use OPAC and problems encountered during usage. Hence, students have not been making effective and efficient use of the library OPAC. Therefore, we recommend that the Library should create more awareness and effective education for students at various levels to ensure maximum utilization of library resources.