Electronic information resources (EIRs) referred to information that are available in electronic format. These resources are very useful in postgraduate education, but it was observed that some factors determined the use of these resources among the postgraduate students who are expected to use EIRs that are provided in libraries. In line with this, this study investigated influence of demographic characteristics on utilisation of EIRs by postgraduate students in three selected universities in south-west Nigeria. Descriptive survey research design was adopted for this study. 362 respondents represented the sample size for the study. Statistical Package for Social sciences (SPSS) was used to compute the data, while frequency distribution, mean, percentage, standard deviation and chi-square were used for data analyses. The findings revealed that a significant (P< 0.05) association exist among highest qualification (χ2=40.3), Age (χ2=20.4) and utilisation of EIRs by the postgraduate students. It was recommended that the library management should provide adequate awareness programmes that will promote the use of EIRs among postgraduate students irrespective of age and qualification. Academic staff should advocate the use of EIRs among postgraduate students. This is achievable in a situation where lecturers introduce the use of EIRs to their course-work/ assignments. It was concluded that Age and highest qualification were found to be major determinant of the use of EIRs by the postgraduate students in the selected universities. This is an issue that needed a serious attention because the older postgraduate students are expected to deliver academically as the younger postgraduate students.