The purpose of this study was to determine the influence of demographic and institutional factors on utilisation of online library services by distance learners of the University of Nairobi. Specifically, the study aimed at achieving eight objectives: viz. examine the influence of learners’ gender on utilisation of online library services; determine the influence of learners’ age on utilisation of online library services; assess the extent to which learners’ computer literacy influences utilisation of online library services; establish the influence of learners’ awareness of availability of online library services on utilisation of online library services; asses the influence of learners’ programme of study on utilisation of online library services. The study was anchored on the positivist research paradigm. Descriptive survey and correlation research designs were adopted for this study. Data were collected using self-administered questionnaires and interview schedules. The target population consisted of 1671learners in the School of Open and Distance Learning and 14 librarians found in the University of Nairobi namely Kikuyu Campus, Chiromo Campus and the main library Campus (The Jomo Kenyatta Memorial Library). The sample size was 312 respondents. A pre-test study was conducted using 31learners and 1 librarian. This constituted 10% of the study sample. The researcher tested for the inter-item reliability of the instruments using Cronbach’s Alpha and results ranged from 52.5%-95.8% for learners’ questionnaires while that of librarians recorded 69.8%. Data analysis were done using frequency counts, the mean and standard deviation while hypothesis was tested using multiple linear regression analysis; one way analysis of variance at0.05 level of significance.