Although higher education systems in developing countries such as Iran have embraced the online education approach, they are confronted with significant challenges in this transition, one of which is lack of instructors' participation in online teaching. Therefore, this research is aimed at exploring barriers and influential factors for this lack of participation. The researchers developed their theoretical framework based on a thorough review of the existing body of knowledge while considering the cultural features of Iran as a developing country. A tailored questionnaire asking about the existence of three groups of barriers, namely personal, attitudinal and contextual inhibitors, was distributed among all faculty members who were candidates for delivering online courses in one of the top universities in the country. Data was analysed using the descriptive and inferential tests of Friedman, tTest and ANOVA. The results were in line with research findings in other developing countries in which the contextual barriers had the most inhibition effect against faculty members' participation in online teaching. Certain cultural barriers also are highlighted by participants, pertaining to the context of Iranian online education systems.