The practice of e-commerce has become familiar in developed countries long years ago, but it is still at infant stage in developing countries. In Ethiopia, despite the fast growth of ICT infrastructures the practice of e-commerce is still in the first stage. Many factors could be a cause for low level of e-commerce adoption. This study is aimed at identifying the most important barriers that influence large and medium scale manufacturing industries in Ethiopia in order to adopt e-commerce. In this study, 330 large and medium scale manufacturing industries were selected using simple random sampling method. The data was collected from company managers using self-administered questionnaires which incorporated 26 barriers organized in to social & cultural, technical, economic, political, organizational, and legal & regulatory barriers. The finding of the study shows that the top barriers identified were related with lack of einfrastructure, lack of e-trading legislations, external environmental factors and insufficient awareness about the benefit of e-commerce. In addition, the result from the t-test claimed that barriers identified in the study has a more influence on non-adopters than adopters. The paper has suggested recommendations for overcoming the barriers of adopting e-commerce in Ethiopia. This paper also contributes a lot for researchers who are interested to investigate about the barriers of adopting e-commerce in others sectors.