Online databases have been created for use by students and researchers of which postgraduate students constitute a major part. However, past studies have revealed low utilisation of online databases by postgraduate students and observations have shown that adjustment factors (perceived enjoyment and objective usability) could be responsible. This study examined the relationship between adjustment factors and the use of online databases by postgraduate students in four private universities in South-West, Nigeria. The research design employed for this study was the descriptive survey of the correlational type. Population comprised one thousand and sixty seven (1067) postgraduate students in four private universities (Afe Babalola, Babcock, Lead City and Redeemers) Purposive sampling technique was used to select two common faculties and a sampling fraction of 70% of the population of each faculty was used to select the sample size of 513. Data was collected using questionnaire and analysed using descriptive and inferential statistics (pearson moment correlation, multiple regression and ANOVA). Findings revealed that there is a significant relationship between: perceived enjoyment and use of online databases in Afe Babalola, Lead City, and Redeemers universities; objective usability and use of online databases in Afe Babalola, Babcock and Lead City universities. Postgraduate students are likely to continue to use online databases if they perceive the usage to be enjoyable and if they are able to perform their various academic tasks with the online databases.Â