Online instructors in higher education play a key role in the success or failure of electronic learning systems (ELSs). Their expertise in and use of technology tools in ELSs influence the quality of information presented, their system use and satisfaction during course delivery. This study adapted Holsapple and Lee-Post's ("Decis Sci J Innov Educ" 4(1):67-85, 2006) model to examine online instructor e-learning readiness (e-readiness) at the online campus of a Caribbean university, and to assess their levels of e-readiness and impact before, during and after course delivery. Responses from 208 online instructors were analysed from an online survey. Results show that while the cohort was 90.6% e-ready, only 72.6% were individually e-ready by having access to a dedicated network connection for substantial periods of time, routinely communicating with persons using electronic technologies, being self-motivated and independent learners, with a predisposition towards embracing and using new technologies. During the pre-course phase, online instructor e-readiness had a moderate impact on both technical (ELS quality and service quality) and non-technical (information quality) aspects of the ELS. During course delivery, its influence decreased with the technical aspect (ELS use) but increased with the non-technical aspect of the course (instructor satisfaction). At course completion, the main benefit was enhanced teaching skills while lack of contact with others was the main challenge. The results could be used to identify characteristics of online instructors suitable for the online environment, monitor their impact during the phases of a course, and serve as a benchmark for comparing levels of e-readiness across institutions.